45.

2.5

=

=

18. The volume occupied by the atom of oxygen in this compound volume of potash Jume of potassium 18-44.11= -26.11; so that, 37.5 parts of potassium occupy a volume which may be represented by 44.11; by combustion, it combines with 7.5 parts by weight of oxygen, and the volume becomes 18; consequently the space occupied by the oxygen is negative, i. e. 26.11 of space less than 0, which is absurd." He endeavours in vain to explain this absurdity of the atomic theory ; and finally concludes, "there is no parallel." We have no doubt, however, that as the theory is pushed through all its consequences, many parallels to this in absurdity will be discovered.

In a paper on Mr. Daniell's work on Hygrometry, we find the following observations, which may be useful to some of our readers, as stimulating them to turn their attention to making barometers; and to others, as warning them not to place too much faith on these, at present, ill-made instru

quality of their tubes and the excellence of the filling, in one who has but indirect interest in the matter, or equivocal reputation to lose; responsibility is thus shuffled from both, and rests on neither. Such, however, are the people who by unaccountable prescription supply the city of London, and the philolosophers of England, with the instruments which Mr. Daniell so well describes.

"If common notoriety did not bear Mr. Daniell out in his assertions, the shameful disagreement of the thermometers used by Captain Parry in his last voyage would fully do so. On one occasion this amounted to no less than 13 degrees; Capt. Parry could do nothing else than give a mean, though in such a case 48° had as good a chance of being. the truth as

UNEQUAL

DISTRIBUTION

OF HEAT IN THE PRISMATIC SPECTRUM. THAT the different portions of the prismatic solar spectrum possess different heating powers, has been universally admitted by every philosopher who has examined the subject experimentally; but a great diversity of opinion has prevailed respecting the precise point where this power resides in its greatest intensity. Landriani, "one of the first who investigated this subject, placed the maximum heating power in the yellow rays, Rochon in the orange or orange yellow, and Senebier also in the yellow. Herschel, on the contrary, found the heating power of the red to be superior to that of all the other coloured rays; but that there is a certain point of the spectrum, situated immediately beyond the red and invisible, which elevates the thermometer still higher than any of the visible rays. His experiments were directly contradicted by Leslie, but were soon after, in a great measure, confirmed by Englefield. Dr. Seebeck, in a memoir read to the Royal Academy of Sciences in Berlin, which, with numerous original experiments, com

bines a copious discussion of the opinions of preceding inquirers, appears to have ascertained the cause of those anomalous statements. It exists in the particular nature of the medium by which the rays of light are decomposed; a eircumstance so little regarded, that few experimenters have even deemed it necessary to record the material of their prism. The following is a summary of his results.

In every part of the prismatic spectrum there is a perceptible elevation of temperature, and this is uniformly least in the outermost edge of the violet. From the violet it gradually increases, as we proceed through the blue and green into the yellow and red. In some prisms it attains a maximum in the yellow, as, for example, in those filled with water, alcohol, or oil of turpentine. In others, as in those filled with a transparent solution of sal ammoniac and corrosive sublimate, it attains a maximum in the orange. Prisms of crown glass and of common white glass have the maximum of temperature in the centre of the red; others, which appeared to contain lead, have the maximum in the limit of the red. Prisms of flint glass have the maximum beyond the red. In all prisms, without exception, the temperature regularly diminishes from beyond the red; but it still continues perceptible at a distance of several inches from the extremest limit of that side of the visible spectrum.-Schweigger's Neues Jour nal, vol. x. p. 129.

CONVERSION OF HONEY INTO SUGAR.

THE Jews in Moldavia and Ukrane have a method of making honey into a hard and white sugar, which is employed by the distillers of Dantzic to make their liqueurs. The process consists in exposing the honey to the frost during three weeks, sheltered from the sun and snow in a vase of some material which is a bad conductor of caloric. The honey does not freeze, but becomes transparent and hard as sugar. Hanoverisches Magazin.

ATTRACTION OF PARTICLES OF GASES.

Woolwich, Sept. 3.

THE study of any science, particularly that of chemistry, is pursued with more facility and pleasure, the more clearly the facts connected with it are stated and the phenomena it presents are more accurately viewed. To accomplish this being one principal design of your publication, encourages me to offer the following observations.

All the chemical authors which I have read, when treating of the three forms of matter (solid, liquid, and aeriform,) assert that the gaseous is that state in which the attractive force is entirely overcome, and the repulsive has gained the ascendency, or that the particles of gases are mutually repellent.

Now, Sir, in first reading these assertions, I was very much perplexed, for I cannot conceive how substances can exist while their particles repel each other; indeed, were this the case, I should imagine that the moment substances assumed this form, they would fly off in all directions, and constitute an indiscriminate and heterogeneous mixture with the atmosphere and each other; consequently we should not be able to obtain any such thing as a simple gas.

But from a more minute consideration, I think a very cursory view of the subject will prove that every species of attraction exists in the gaseous as well as any other state, e. g. take two volumes of carbonic acid gas, pour them into an open vessel, it will displace the atmospheric air, combine, and form one volume equal in bulk to both; it may also be allowed to remain in the vessel for a considerable time without mixing with the atmosphere: its particles, therefore, possess sufficient attraction to each other to cause them to unite, and preserve their identity after they have united; and this experiment may be performed with any other gases, where the difference of specific gravity is sufficient, and no particular chemical affinity exists;

and this I consider the attraction of aggregation, in the strictest sense of the word.

It were unnecessary to attempt to prove that the attraction of gravitation or combination exists in the particles of gases, as that is evident from their weight, and this sufficiently obvious from the numerous instances of gaseous combination, which all your readers must be acquainted with.

If you consider these remarks deserving a place in your useful work, they are at your service; and by inserting them you will oblige

Your humble servant
and constant reader,
J. ALWIN.

To FREEZE ONE LIQUID AND
BOIL ANOTHER
SAME MEANS.

BY THE

THE old story says, that the satyr turned the hungry and half-frozen traveller out of his cave for blow. ing hot and cold with the same breath. The manner in which heat is distributed has taught us that in this instance, at least, man was right and the satyr wrong. But if this surprised him, what would he think of the wonders of modern chemistry, of seeing, for example, one fluid frozen and another made to boil by the same means? If we take, for instance, a small tin cup of ether, put it within a watch glass containing water, and place both under the receiver of an airpump, it will be found, on exhausting the receiver, that the water will freeze and the ether boil. The reason is, as the air is expanded, the ether, by its own caloric, and absorbing caloric from the water, is converted into a gas, which escapes in ebullition, while the loss of caloric suffered by the water converts it into ice.

(but at the same time equally eligible) cannot be made use of than the one at present employed in tanning. I am, Sir,

# Your obedient servant, Manchester. INQUISITUS.

Is there any liquid or prepáration known, with which a room, ornamented with size-colouring, may be washed, so as not to shine like varnish, and which will bear cleaning with water?

ELECTRICITY BY WATER FREEZING.

WHEN water is frozen rapidly in a Leyden jar, the outside coating not being insulated, the jar receives a feeble electrical charge, the inside being positive and the outside negative. If this ice be rapidly thawed, an inverse result is obtained; the inside becomes negative and the outside positive.Quarterly Journal of Science.

TO DETERMINE SPECIFIC GRAVITIES.

Ir the body be a solid, fill a phial with water, and note its exact weight in grains. Take a hundred grains of the substance to be examined and drop it into the water; now weigh the phial again, and the difference between its present and former weight will give the specific gravity of the substance. If the body be a liquid, a bottle or phial, the weight of which is known, and which holds exactly five hundred or a thousand grains of water, is to be filled with the substance and weighed: the weight, deducting the weight of the bottle, will be the specific gravity of the substance. For example, if the bottle contain a thousand grains of water, and be filled with sulphuric acid, it will be found to weigh from 16 hundred to upwards of 18 hundred grains, and the weight will be the specific gravity.*

*For an explanation of specific gravity, see Chemist, No. XXIV., Article, Chemistry.

DESCRIPTIVE HISTORY OF THE STEAM-ENGINE.

(Concluded.)

AFTER Savery's engine became known, a great deal more attention was directed to the subject than before; and the names even of those who were successful in their attempts to improve it, would occupy no inconsiderable space. In Savery's engine, the effect is produced by the condensation of the steam forming a vacuum in a receiver, into which the water is forced by the pressure of the atmosphere; and where the water was required to be elevated to a greater height than from 28 to 30 feet, he employed the direct pressure of steam of a high pressure and dangerous elasticity." It could only,

4

however, be applied with safety to raise water about 30 feet. A very short time after the publication of Savery's book, Thomas Newcomen, a blacksmith, and John Cawley, a glazier, both living in the town of Dartmouth, in Devonshire, "made the experiment of introducing steam under a piston moving in a cylinder, and formed a vacuum by condensing the steam by an effusion of cold water on the outside of the steam vessel, and the weight of the atmosphere pressed the piston to the bottom of the cylinder. This was the first form of the atmospheric engine, the simplest and most powerful machine that had hitherto been constructed. In the atmospheric engine the process is totally different from that in