AND POPULAR SCIENCE REVIEW. VOLUME XVI. CONTENTS. FAMILIAR SCIENCE. -How Spiders Fly........ About Volcanoes..... Experiments for Young Chemists. Miso.... Scientific Brevities... Household Hints...... PRACTICAL Chemistry anD THE ARTS. try.. Specific Gravity of Ether........ Industrial Memoranda. Practical Recipes.. Miscellanea.. AGRICULTURE. A Farmers' School... 1 Bridgewater Meeting of the State Board of Agriculture.. The Soil as a Laboratory. Gleanings......... EDITORIAL. - Boston Water... The Metric System.... Underground Telegraphy... What is said about the Journal Meteorology for November, 1881. Literary Notes... 2233 5 5 5 BOSTON, JANUARY, 1882. a bell glass was placed over the pail, thus pre- But how does it happen that, on setting out 4 by pulling in her thread, she reduces her floating NUMBER 1. and neither their buoyancy in sunshine, nor their gravity in shadow, will be particularly noticeable. PRINCETON, N. J., November 11, 1881. ABOUT VOLCANOES. THE popular idea of a volcano does not differ from the definition given in the school geographies: "A volcano is a burning mountain, from the summit of which issue smoke and flames; but, as Professor Judd remarks in his recent book on " Volcanoes, What they Are, and What they Teach," this description "is not merely incomplete and inadequate as a whole, but each individual proposition of which it is made up is grossly inadequate, and, what is worse, perversely misleading." A volcano is not necessarily a mountain, though it often forms a mountain by the heaps of matter it throws forth. tially, it is a hole in the earth's crust, an outlet. from the interior of our globe. It may exist, and often does, at the bottom of the sea, and in such cases it will not appear above the surface until it has built up an island with the ejected material. In the course of time the island may become a lofty peak, like Stromboli, in the Mediterranean, whose summit rises more than three thousand feet above the level of the sea. Essen But this is not all unless I am much mistaken, the action of the sun's rays on the thread itself and its surrounding envelope of air is the main cause of its buoyancy. Air is nearly dia12 thermanous, or transparent to heat, so that the 12 solar rays, in traversing it, warm it only slightly. The spider's thread is not so, but in the sunshine warms up almost instantly, heating the air in immediate contact with it; and then, although the spider-thread alone is heavier than air, yet the thread and the adhering envelope of warmed and expanded air, taken together, are lighter than Again, a volcano is not a "burning" phethe same bulk of the cooler air around, and thus nomenon, though it looks much like it. The constitute a quasi-balloon, on which the spider violent action is not combustion in any sense. sails away. Of course, if this is so, the poor Neither does the eruption always occur at the creatures cannot sail much on cloudy days, and I" summit" of the mountain, being quite as often think, in fact, they do not. I was very much interested, a few days ago, in hearing a friend give an account of a manuscript she had seen, which was written by Jonathan Edwards when nine years old. It was an account of the behavior of certain small New England spiders, the manner they fly through the air, and the way to see them best, by getting into the edge of a shadow, and looking towards the sun. It is neatly and carefully written, and illustrated by little drawings, very nicely done. The philosophical tendencies of the young writer already appear, for his conclusion as to the "final cause" of spiders and their flying is this: the little animals are scavengers, and since, in New England, the prevailing winds are west, they are carried to the sea in their flight with whatever filth they have consumed, and so the land is cleansed. Every one knows how, in sunny weather, the little creatures, standing on their heads, project from their spinnerets fine filaments of gossamer, which are caught by the breeze, and float off into the air, though still attached to the spider. When she perceives that the thread is long enough, and the pull of the wind sufficient, she releases her hold, and flies away on her gossamer like a witch on her broomstick; by watching her chance, and letting go only when the breeze is favorable, she is carried to her desired haven. Experiments have been tried by placing the animals on a chip floated in a pail of water. So long as the air was in motion about them they were able very soon to escape from their island; but when I have tried a few experiments to verify the idea, and so far as they go they all confirm it. For instance, one day in the autumn of 1880, when the air was full of floating gossamer, and there was no wind blowing, I caught some of the filaments at the end of a little stick, to see how they would behave. So long as I stood in the sunshine they streamed straight upwards, tugging with almost a breaking strain; as soon as I stepped into the shadow of a building, they lost their spirit, and drooped abjectly; the moment I put them in the light again they resumed their buoyancy. It is of course possible that in the shade there were local downward air currents to account for their behavior; but once a cloud passed across the sun, and they drooped then, just as they did behind the building. from its sides or its base. The present crater of Stromboli is some distance below its top, and one can look down into it from points higher up on the mountain. On this account, and because the volcano is constantly in a state of moderate activity, it affords a peculiarly favorable opportunity of watching and studying the phenomena of eruption. Neither "smoke" nor "flame" issues from the volcanic crater, as the definition we have quoted asserts. That which seems to be smoke is really condensing steam or watery vapor, and what looks like flame is merely the reflected glow from the molten lava beneath. If the vapor were not there to reflect the light we should see no "flame," nor anything suggestive of it When Vesuvius is quite inactive, as it was when we visited it in 1879, one sees nothing by day to The same theory will explain the buoyancy of indicate its volcanic character except the steam any minute particles of dust or smoke. So long slowly rising from its top; but at night this steam as the sun shines, they will absorb its rays, be- is lit up with a ruddy glow at intervals, as the come warmer than the air, and surround them-ever-seething caldron below bubbles up with inselves with a buoyant envelope, which will carry creased vehemence and becomes incandescent. them up, if they are not too heavy in proportion In a great eruption, enormous volumes of steam to their surface. But if the air is still and the are poured forth, sometimes rising to the height sun obscured, they will settle down near the of twenty thousand feet, or about four miles; and earth, in the way we are all familiar with in when these are illuminated by the intense light muggy weather. Of course, if there is much of immense lava streams, overflowing the crater wind, this will mainly control their movements, in all directions, and rolling down the sides of the fire. mountain, it seems as if the world were on vast bulk of the earth, it is of the slightest and with hot water. This residue, KHSO4, was formost superficial character. The upheaval of the merly known as bisulphate of potash. Its weight The tremendous nature of this volcanic energy loftiest volcano from the surface of the globe is should be over 13 grams, and if there were no and its mountain-building work were both strik- relatively more insignificant than the development loss of nitric acid we should get over 6 grams of ingly illustrated in the formation of Monte Nu- of the smallest pimple on a man's body; and all that. The acid will have a red or yellow color, ovo, on the shores of the Bay of Naples, a few the torrents of lava and ashes that the volcano which will disappear if left standing in an open miles north of the city, in the year 1538. From ejects, though devastating the region round about vessel. Several interesting and instructive exa spot of level ground, water, at first cold, but and burying cities and towns, are scarcely com- periments can be made with it. Pour a few afterwards becoming warm, began to issue; then parable to the "matter" that exudes from the drops of it into four different test tubes. In one the earth cracked open, displaying incandescent tiny pustule. A grain of dust on a varnished of them put a piece of copper, in another a matter within the fissure. Soon masses of stone, globe a foot in diameter would represent the ris- piece of iron or a nail, in a third a piece of pure with vast quantities of pumice and mud, began to ing of Monte Nuovo, and a fine scratch on the tin foil, and in the last a strip of silver or a small be thrown up to a great height, and this con- smooth surface would be relatively as deep as the silver coin. Red fumes will be given off from tinued for two days and nights, forming a hill greatest of volcanic fissures. The vulgar notion all except the iron. The copper and silver will more than four hundred feet high. Less violent that these cracks break through the whole crust dissolve; the tin will form a white powder of eruptions followed at intervals during the next of the earth to the central molten mass within oxide of tin, but will not dissolve. If the tube five or six days, when the volcanic action ceased, if such, indeed, there be — is based upon a child- containing the iron is heated, the iron will disand the place has been undisturbed ever since. ish misconception of the size of our planet. The solve, too. Gold and platinum are the only Monte Nuovo is now a smoothly rounded hill, phenomena appear vast and tremendous only be- metals not attacked by nitric acid; hence it was covered to its summit with a dense growth of cause we ourselves are creatures so infinitesi- called aqua fortis (literally, strong water), and pines; and as you ride past it, on an excursion to mally small that it is not easy for us to measure was employed to separate gold from silver and Lake Avernus (itself probably a crater, now con- them in their relation to the great sphere of eight other metals. If nitric acid touches the skin it verted into a quiet and lovely little pond, with thousand miles in diameter on which they occur. forms a yellow stain, which remains until the skin nothing to suggest its ancient terrors) and the To a mighty angel flying through the regions of wears off. On black cloth it produces a brown ruins of Baiæ, you would never suspect that, space near our earth, the most violent of vol-stain that cannot be removed. instead of being one of "the everlasting hills "canic eruptions would be less noticeable than the which fill the landscape, it was the sudden product of volcanic forces only some three centuries and a half ago. Many theories of volcanic action have been framed, but no one of them is entirely satisfactory. Professor Judd, in summing up the results of the latest investigations, is obliged to admit that "we do not at present appear to have the means for framing a complete and consistent theory." scratching of a match a dozen rods off to yourself EXPERIMENTS FOR YOUNG CHEMISTS. IV. NITRIC ACID. If we put a single drop of nitric acid in a test tube full of water, and then drop into it a strip of blue litmus paper, the latter will change to red. All substances which are able to produce this change are called acids. We shall subsequently find that all acids contain hydrogen, thus: hydrochloric acid, HCI; nitric acid, HNO,; sulphuric acid, H2SO4; phosphoric acid, H,PO, An acid may be defined as a compound of hydroTHIS acid, HNO3, is made by the action of gen, which, if soluble, will redden blue litmus, strong sulphuric acid upon potassium nitrate and the hydrogen is replaceable by a metal. It is a curious fact that volcanoes, almost with- (saltpetre), and the reaction is represented by When silver dissolves in nitric acid the metal out exception, are either on islands or along the the following formula: KNO, + H2SO1 = takes the place of the hydrogen in the acid, and shores of the continents. All the oceanic islands KHSO4 + HNO3. Into a two-ounce (60 cc.) tu- the resulting compound is called a salt. Nitric that are not coral reefs are of volcanic origin, bulated retort, like that shown in Figure 6, put acid, HNO3; silver nitrate, AgNO3. and many of them are still the scenes of volcanic 10 grams of pure potassium nitrate, in fine powTesting for Nitric Acid.. Dissolve a little activity. A continuous ridge in the Atlantic, der, and pour upon it, through a funnel inserted potassium nitrate in a test tube, and drop into it along which lie the islands of Jan Mayen, Ice- into the tubulure, an equal weight of strong sul-a land, the Azores, Canaries, and West Indies, phuric acid. Replace the glass stopper, mix the contains forty active volcanoes and many extinct substances by shaking the retort very gently, and A similar line in the Pacific, including the support it in the manner shown in the figure, islands southeast of Asia, has a hundred and fifty active volcanoes, or nearly half of the whole number on the globe. Another great stretch of volcanoes, numbering eighty or so, is that along the western coast of the American continent, from near Behring Straits to Terra del Fuego, the "Land of Fire." ones. This proximity of volcanoes to the ocean has led to the theory that their action is due to the penetration of sea-water through cracks in the earth's crust to molten matter within. The chemical reactions that would follow, together with the expansive force of the enormous quantities of steam that would be formed in the confined space, are sufficient, it has been thought, to account for all the phenomena. There are difficulties, however, in this theory, as in all others that have been proposed, though we have not space to enlarge upon them here. At the same time, we must say that they do not appear to us to disprove the theory, and we cannot help regarding it as at present the most plausible explanation of volcanic action. Stupendous as this action on its grandest scale must seem to us human insects, we should bear in mind that, when viewed with reference to the & Fig. 6. Preparation of Nitric Acid. crystal of ferrous sulphate, FeSO4, or green vitriol. Then pour carefully down the side of the test tube two or three drops of strong sulphuric acid. As soon as it touches the green crystal a dark brown cloud will be seen to surround it and form a ring above the acid. This is very characteristic of nitrates. All nitrates are soluble, and hence we cannot make use of any reagent to give a precipitate with nitric acid. In a free state it gives red fumes with copper, and bleaches indigo. Mix 1 cc. of nitric acid with 25 cc. of water, and add to it, drop by drop, some dilute ammonia. After a time it will be found that it no longer reddens blue litmus paper. The acid has been neutralized by the ammonia, and we have a solution of ammonium nitrate, NH4NO3, the substance used in making nitrous oxide, NO. MISO. pieces of wet paper or cotton can be loosely in- Correction. In our last number the formula The rice is first soaked in cold water for two days; then drained, and put into fresh water, and steamed for three hours. It is taken out while hot, and spread on the floor of a warm room for four days, when it is found to be covered with an abundant growth of fungus. It is then taken from this close, damp room to a large, airy one, and spread on mats to cool for an hour and a half, and then transferred to small trays, where it is allowed to cool as rapidly as it can. As soon as cooled it is mixed with the beans, which have been boiled for six hours and allowed to cool over night in the boiler. The salt is also added, and the whole thoroughly reduced and incorporated in long mash-boxes, using a round pole as a pestle. The salt, it should be stated, is very impure solar salt, containing sticks, straws, and dirt. The mixture, when it has been converted into a stiff, pasty mass, is placed in large vats, holding 87 bushels, and packed solid by the feet. The temperature is kept as low as possible, and a slow fermentation goes on for six or eight months, at the end of which time the miso is ready for the market. It forms a thick pasty mixture, of repulsive appearance and disagreeably sour odor. SCIENTIFIC BREVITIES. the glass are found to be deeply etched upon its sur- all cases examined the less refrangible rays pre- distinct. ANOTHER GREAT ENGINEERING SCHEME. The NITROUS OXIDE AS A DISINFECTANT. system employed at the Hôpital de la Pitié, in Paris, for disinfecting sewer gas by means of nitrous oxide Some of our leading engineers suggest a plan for is described in La Nature. The gas passes into an utilizing the vast water supply of the extreme north-earthenware cylinder about four feet in height, filled ern part of the continent. By closing the northerly with charcoal, sprinkled with nitro-sulphuric acid. outlet of the valley of the Mackenzie River at the The moisture contained in the gas condenses on the line of 68°, and thus storing up the water of 1,260,- charcoal, setting free the nitrous oxide contained in 000 square miles, to which could be added the the nitro-sulphuric acid, which destroys the sulphuwater of other large areas, a lake would be formed, retted hydrogen and all deleterious matters. of about 2000 miles in. length by 200 of average IMPROVEMENT IN STEAMSHIPS. - The old Cuwidth, which would cover with one continuous sur- nard steamship Persia was one of the finest steamface the labyrinth of streams and valleys which now ships afloat, in her days; yet she required six tons occupy the Mackenzie Valley. It would prove a of coal to carry a ton of freight across the Atlantic never-failing feeder for the Mississippi, and would in her. To-day the steamer Arizona is carrying connect with Hudson Bay and the Great Lakes, and freight across the Atlantic with a consumption of also with the interior of Alaska through the Yakon only one fifth of a ton of coal to a ton of freight. It and its affluents. The connection of the Upper Mis- is mainly by the reduction in the quantity of coal sissippi with Lake Mackenzie would be a compara- consumed that we estimate the progress made in the tively easy matter, and a vast amount of navigable improvement of steamers during the last forty years. water-way would be added to this river. The formation of Lake Mackenzie would also contribute to the proposed ship canal from Cairo (Illinois) to the Gulf of St. Lawrence by the almost straight line which cuts the Wabash Valley, the Lakes Erie and Ontario, and the Lower St. Lawrence. TALKING A HOLE THROUGH A DEAL BOARD. The following is from the London Athenæum : One day, at Menlo Park, Mr. Edison had been showing his phonographs and telephones to a friend, who at last remarked, in a kind of despair, "Mr. Edison, you had better invent a machine to talk a hole through a deal board." In a week the machine was complete, and may now be seen in the exhibition. It consists of a mouth-piece, with a diaphragm across it, to the centre of which a light steel rod with a ratchet at the end is attached. On being sung to, the diaphragm and the rod vibrate rapidly, and the ratchet, gearing into a little cog-wheel, causes The axle of the cog wheel carries a Many inventors may have had as many brilliant ideas, few have carried out so many in actual practical form. The secret of Mr. Edison's success in this direction may be summed up in his own words: "Whenever by theory, analogy, and calculation I have satisfied myself that the result I desire is impossible, I am then sure that I am on the verge of a discovery." TONGUES AND GIZZARDS. A recent English writer says: The common snail sets forth to ravage our gardens equipped with 150 rows of stout serrated teeth. The whole palate contains about 21,000 teeth, while a full-grown slug has over 26,000 of these silicious spikes. The whelk has a ribbon-like tongue, contained in a proboscis, with which it bores holes in the shells of the mollusks which form its - food. The tongue has strong, saw-like teeth on the edges, with rows of finer ones between. In some it to revolve. mollusks the tongue resembles a tessellated pave-minute drill. ment, with a tooth in the centre of each lozengeshaped compartment. But although the palatal system of the snails forms a powerful and most efficient apparatus for triturating their food, it more closely resembles the gizzard of birds than the teeth of quadrupeds, and it is in the class of fishes that we find the first examples of true teeth, set in a bony socket and ranged at the opening of the alimentary canal. At what time the fashion of wearing teeth came in we have no means of ascertaining. If, however, the Darwinian theory be correct, at some enormously remote period of time some lucky animal developed the new weapon by a series of fortunate variations, and its possession gave to him and his posterity such a "pull" over their competitors that they were able to set the fashion, which has lasted to the present day. ETCHING GLASS BY ELECTRICITY. La Lumière Electrique gives an interesting note on the Planté method of engraving on glass by means of the electric current. A concentrated solution of nitrate of potassa is poured over a sheet of glass placed horizontally in a shallow tray. A platinum wire, which constitutes one electrode of a Planté battery of fifty or sixty elements, is placed in the saline solution near one side of the tray. The other electrode, also of platinum, is surrounded, except at its point, with some insulating material, and serves as a pen for writing. Any characters traced upon THE ACTION OF Oxygen on MERCURY. It is currently believed that oxygen combines to a small extent with mercury at ordinary temperatures, but recent experiments of M. Amagat, communicated to the French Academy of Sciences, have demonstrated that when both these bodies are pure and dry they are without action upon each other, at least for a considerable time. The above error was introduced into science on the high authority of Regnault. M. Amagat arrived at his results by means of a Pouillet apparatus, having nitrogen in one manometer and oxygen in the other, with the metal in presence of both. Although kept for more than a month in the apparatus, the surface of the mercury in presence of the oxygen remained as brilliant as that in presence of the nitrogen. WHAT IS SULPHUR ? - Less than a hundred years ago this question was answered by Stahl as follows: Sulphur consists of oil of vitriol (sulphuric acid) combined with combustible essence. Sulphur can be made out of sulphuric acid, he said, by heating it with charcoal dust, because the latter contains the combustible essence or being. But this combustible essence had not been isolated and obtained in a free state, which seemed to puzzle some of the skeptics of that day, and led them to deny the existence of oil of vitriol in the sulphur. COSMICAL HAIL. M. Shevedoff, a Russian scientist, advances the remarkable hypothesis that hail is of cosmical origin, and captured by our world in its journey through space in the same manner that meteorites are attracted to our planet. He does not, however, explain why the heat generated when the hailstones strike our atmosphere does not melt them. HOUSEHOLD HINTS. A STRONG AND HANDY CEMENT. - One of the strongest cements, and very readily made, is obtained when equal quantities of gutta percha and shellac are melted together and well stirred. This is best done in an iron capsule placed on a sand-bath, and heated either over a gas-furnace or on the top of a stove. It is a combination possessing both hardness and toughness, — qualities that make it particularly desirable in mending crockery. When this cement is used the articles to be mended should be warmed to about the melting point of the mixture, and then retained in proper position until cool, when they are ready for use. EARACHE. In the American Medical Association, Dr. Jacobi remarked that closing the mouths of infants and children, and simply blowing into the nose, is often a very valuable method of relieving severe earache, and that in a number of cases he had obtained most excellent results from this procedure, the cause of the trouble probably being a catarrhal affection of the Eustachian tube. SYRINGING THE EAR. Let it be laid down as a rule from which there is to be no departure, says the Atlanta Medical and Surgical Journal, that no ear should be actively syringed unless there is something in it which it is important to remove. Cold water should never be put into the ear. PIMPLES ON THE FACE. SPECTRA OF FIRE-FLIES. During the past summer Mr. W. G. Levison, of Brooklyn, N. Y., has studied the spectra of the light of fire-flies and other light-producing insects. He finds that the ordinary small species of fire-fly gives a spectrum from Dr. Gage Parsons which the blue and violet are omitted, and that in recommends to dust the face with pure precipitated sulphur every night with an ordinary puff used for Practical Chemistry and the Arts. INDICATORS FOR ALKALIMETRY. IN volumetric analysis, when it is desired to determine the strength of a given acid by ascertaining how much normal alkali is required to saturate it, or the reverse, it is necessary to employ an indicator which shall mark the neutral point. It is not our design to add to the list of substances proposed for that purpose, but to enter into a critical examination of those now in use. The most common and one of the best is LITMUS. It comes into the market in small cubes, of a blue color, which contain an excess of alkaline carbonate. It is best prepared for use as an indicator by first extracting three or four times with strong alcohol, which removes a peculiar coloring matter that would interfere with its use as an indicator. It is then extracted with cold water, filtered, and enough acid added just to neutralize the alkali in it. It keeps its color best when left uncorked in half-filled bottles. With caustic alkalies it forms a deep blue color, that changes suddenly to an onion red when an excess of acid is added. If, however, carbonates are present, the blue changes to a purple before the alkali is saturated, and the change to red is For this reason carbonated alkalies must be titrated hot, and the liquid boiled between each successive addition of acid as the neu uncertain. tral line is reached. With this single drawback litmus is an excellent indicator. There are cases, however, where neutral salts (those in which all the hydrogen of the acid is replaced by metals) give an alkaline reaction with litmus. This is the case with sodic acetate. COCHINEAL. These are small bugs which grow on a species of cactus in Mexico. The solution is prepared by digesting three grams of cochineal bugs (whole) in 250 cc. of dilute alcohol, made by mixing three or four parts of water with one of alcohol. The solution is acid to litmus, and must be carefully neutralized. It has a deep carmine red color in alkaline solution, which changes to yellow when acid is added in excess. It is much better adapted to the titration of alkaline carbonates than litmus. It is not affected by weak acid, and hence cannot be used in determining acetic acid. The results obtained in titrating alkalies with litmus and with cochineal do not agree perfectly; hence the same indicator must be used in standardizing the solution as will be employed in the analysis. CORALLINE. it a deep yellow color. If enough alkali is added ing an excess of ammonia, and then saturating the solution with hydrosulphuric acid gas. It is red in alkaline, yellow in acid, solutions. PHENOLPHTHALEINE. To insure neutrality in the indicator and guard against possible error, the following method may be employed with this as well as other inThis substance was discovered in 1871 by dicators: Take about 100 cc. of water, and add Professor Baeyer, who obtained it from the acto it a drop of alkali and enough of the indicator tion of sulphuric acid upon a mixture of phenol to impart to it a deep red color. Having filled and phthalic anhydride. In 1877 E. Luck sug the burette with one tenth normal acid to a point gested its use as an indicator, and since it has become a commercial article (at $2.50 per ounce) somewhere above the zero mark, let one drop fall into this 100 cc. solution; if it does not it seems to have met with much favor among chemists. change add a second drop, and a third if necesOne part of the phenolphthaleine is sary. The change is very marked and sudden. dissolved in thirty parts of alcohol, and one or two Divide this solution into two nearly equal parts drops of this solution are added to the substance in beaker glasses of the same form and size. To one add the alkaline solution that is to be tested, and to the other the same volume of distilled water: the former becomes intensely red; the other should remain unchanged. Now allow the one tenth normal acid to flow into the red solution until its color is precisely the same as that in the other beaker glass, namely, yellow. The delicacy of this reaction is all that can be desired, and it is especially preferred to litmus for determining the strength of acetic acid, since neutral sodic acetate does not color it red. For alkaline carbonates it is inferior to cochineal, for just at the point where litmus turns purple, coralline changes to an orange, which passes gradually into yellow. NITRO-PHENIC ACID not in the market here. water. to be tested. In neutral and acid solutions it is colorless, but a trace of alkali changes it to a beautiful rose color. The change is sudden and very easily seen, but we fail to discover its great superiority to coralline. It does not work well with the carbonates, and this is attributed by Vielhaber to the formation of a bicarbonate which does not affect this indicator. Results obtained with potassium carbonate, as will be seen below, differ about fifty per cent. from those got with other indicators. With acetic acid this indicator agrees very closely with coralline. SALICYLIC ACID. produced by the action of salicylic acid upon salts of iron is destroyed by acids, and changed make use of this property in alkalimetry, but we to a yellow by alkalies. Weiske proposes to believe it is useless as an indicator. It is well known that the beautiful violet color Fluorescene and many other substances have merely the result of our own observation we pass been recommended, but as we set out to give them by. is recommended by Langbeck as an indicator. Litmus O Nitro-phenol Phenolphthaleine 1100, and forms a deep yellow salt with the This substance is easily prepared in the laboratory by heating a mixture of one part oxalic acid, crystallized, one and one half parts carbolic acid, two parts concentrated sulphuric acid, for five or six hours on an oil bath at 140° or 150° C. To nates. prevent loss, a long upright tube may be inserted in the cork to act as a return condenser. The resulting mass is poured into water, when the coralline is precipitated as a resinous mass. It is but slightly soluble in water, yet imparts to PICRAMIC ACID. |