with ammonia forms a soapy emulsion. Nitric acid heated on it dissolves and converts it into oxalic acid. It resembles refined bees'wax, and serves for making candles. The fibrous substance is procured by decanting the melted waxy matter, washing off the last portion of it with an essential oil, squeezing the residuum, and boiling it a long time in water, to volatilize the oil, the odour of which cannot, however, be completely discharged. Thus obtained, the fibrous matter is brown, having been somewhat altered by the temperature of the melted wax. It is tasteless. Placed on a hot iron, it twists itself and swells up, melts, and is carbonized, diffusing the smell of broiled meat. Alcohol does not dissolve it; and hence, by treating the extract of the vegetable milk repeatedly with hot alcohol, the fibrous matter is obtained white and flexible. In this state it dissolves readily in diluted muriatic acid. It possesses the same properties, therefore, as animal fibrine. Fibrine had already been found in the milky juice of the carica papaya, by Vauquelin. Besides these two main constituents, the vegetable milk contains a little sugar, a magnesian salt (not an acetate), and water. It contains neither caseum nor caoutchouc. By incineration some silica, lime, phosphate of lime, and magnesia were obtained. The wax forms about one half the weight of the milk. Annales de Physique et de Chemie.

ATMOSPHERE OF SEAS. M. VOGEL, of Munich, after a num→ ber of researches, from which, judging by his name, (Bird) we should suppose him extremely well qualified, states, that 1st, the air of the channel between Dieppe and Havre contains muriates; 2dly, the air of the Channel, as well as the air of the Baltic, contains less carbonic acid than the air of the Continent; 3dly, the muriates do not disengage their acid at a tem perature capable of bringing them to ebullition, but they are partly

volatilised with the vapours of the water; 4thly, there is no particular colouring principle in sea air, as has been supposed; 5thly, all waters containing muriates acquire a wine red colour, with nitrat of silver, when exposed to the sun.

FIELD MICE.

IN 1809 or 1810, in the month of August, there appeared such quantities of field mice in Morvern, that the inhabitants discovered these were more mischievous enemies than tax-gatherers or excisemen. They disappeared, however, during the ensuing winter, leaving the good people with an opinion, that it was better to have them for a few months than a few years. Every spot of fine pasture in the neighbourhood was cut into roads; the grass, bit through at the roots, lay withered on the ground; bushes, also, nibbled at the roots, decayed and died. The bark of young wood was knawed off, and the ground undermined to such a degree by their subterraneous residences, that it often yielded to the foot in walking. These subterraneous residences were intended for winter quarters; and it was observed the nests all communicated with each is other by means of cross roads, and el every nest had a connexion by one of these roads, with some placet where there was water. At onerit farm in Morvern the crop was completely destroyed; every square foot of the roof of the barn was per forated, and the rods fastening the thatch bit through. The subse quent winter was very severe, and d it is supposed they perished {for}} want of food. These little animals did an immense deal of injury, destroying the young fir-trees, by eating away the bark a little above the root. So ruinous were they to the plantations, that an army of women and cats were stationed,fi night and day, so as to cover the whole domains of a Colonel Mabes lean from the incursions of thism enemy. It would appear, however, that this force was insuffi cient; and, in spite of these sentinels, the Colonel's property was much ravaged.

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boiled in a weak solution of pot and pearl-ashes, are again washed, twice boiled in soap alone, then soured in very much diluted sulphuric acid, washed from the sour, again boiled with soap, washed, and then immersed in oxymuriate of potash. Boiling with soap and steeping in the oxymuriate, are repeated until the muslin is a pure white; it is then soured and washed in pure spring water. In bleaching the finer muslins, such as mull and book, only soap, and no pearlashes, is used. There is a particular kind of cotton goods, called pulicates, the yarn of which is dyed with some permanent colours before it is wove. For a long time, no certain method could be found of bleaching the white of this kind of cloth, without injuring the colours. At length it was ascertained, that if the oxymuriate were neutralised by a considerable quantity of alkali, the permanent colours were rather improved than injured. Since this discovery was made, these cloths have been bleached in this way :--The starch is first well washed out in cold water, they are then boiled gently in a soap ley, and, after being washed, are immersed in a strong solution of oxymuriate of potash. This process is repeated till the white is good, when they are immersed in dilute sulphuric acid. If the goods are properly attended to, the colours are improved, and acquire a delicacy of tint which no other process imparts to them.

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Another process of bleaching was introduced not long ago, by Mr. Turnbull, of Dunbarton, with great success, the principle of which consists in immersing the goods in a strong solution of caustic alkali, and afterwards exposing them to the action of steam in a close vessel. After being steeped in the alkaline solution, they are hung up in this vessel connected with a steam boiler. When thesteam is admitted, the effects of the alkali are increased by the heat, so as completely to dissolve in a few hours the colouring matter of the cloth. They are afterwards washed, and

this process is repeated till the cloth is of a proper whiteness; after which it is soured and washed, as in the ordinary method. Oxymuriatic acid may be employed at proper intervals. Nine steeps, with exposure to steam, is found sufficient for linen, and five for cotton. By this method a considerable quantity of alkali is saved, as none of that which is employed is wasted.

IN BLEACHING CALICOES for the printer, a pure white is not so much the object to be attained, as that the colouring matter and the vege table oil are fully extracted, or the cloth is what is called well rooted. This is effected by boiling and bucking the cloth, if linen, nine or ten times, and if cotton, five or six times, in a solution of alkali, rendered caustic by quick lime. The alkaline solution must be well settled, and transparent as water; because, if the lime remains either suspended or in solution in the water, it is apt to be deposited in the cloth, and destroy the purity of the parts intended to be white. To ascertain if the cloth be ready for printing, a strip is torn from the end, and printed with one of the mordants used to fix the dye. The cloth is then rinsed and immersed in cold water, which contains madder; the heat is gradually increased, and the cloth is alternately lifted up and down in the madder solution, till the colour is dyed of the required shade, If the cloth be properly bleached, the place stained with the mordant will alone have attracted the colouring matter of the madder, and the rest of the piece will remain white. If not properly bleached, the part intended for white will be stained a dirty light red, and it must again be boiled in the solution of alkali.

In bleaching either linen or cotton for printing, it is not customary to immerse them in any oxymuriatic solution, except in winter, when it is difficult to obtain a good white. When exposed also on the green, they are not artificially watered, but are merely exposed to the vicissitudes of the weather;

and hence this method is called dry bleaching.

We now come to the most peculiar part of this branch of bleaching; which is, restoring the white without injuring the colours after the printing is completed. When this is done, the white is generally very dull, owing partly to the imperfect manner in which the cloth has been bleached, partly to the mordant having been loosened by the increased temperature of the water, which uniting with the madder, or other colouring matter, is spread over the parts intended to be white. To remove this dulness without much exposure on the bleaching-green was long a desideratum; it is now effected by means of oxymuriate of magnesia. The usual methods of bleaching, and the application of oxymuriate, either of lime or of potash, either changed the colours or rendered them duller, or wholly discharged them. Oxymuriate of magnesia has neither of these effects; it clears the white without injuring or altering the colours. It has been found by experience, that of all the alkaline earths which are partially soluble in water, magnesia has the least effect in changing colours, which makes it well adapted, when mixed with the chlorine or oxymuriate, to the purpose of clearing the stains from the white of printed goods.

Our plate represents the apparatus now most generally employed to make the oxymuriate of magnesia. A is a furnace; B a cast iron vessel, to serve as a water-bath for the recepfion of C, a still made of lead, and adapted to the cast iron waterbath, in which it stands; dd are water lutes for the still to drop into, which keeps the whole tight and prevents the escape of gas; E is the head of the still, which dips into the gutter of water surrounding the still, and enables the workmen to take it off and put it on without difficulty; fff are pipes and tubes; CC is a stirrer, made of a square piece of wood covered with lead; Ha bent fun

nel for pouring in the acid; I an intermediate vessel to arrest any uncombined acid which arises during the process; K'is a receiver made of lead, into which the alkaline solution is put, and which, when saturated, may be drawn off at N; L is the opening; and M M the stirrer, which, in large works, is moved by being connected with a steam-engine, or some other power. In preparing the magnesian solution, the earth must be broken in water like starch; it is then introduced into the receiver, K. Into the still, C, is put one part of good manganèse, on which is poured two parts of muriatic acid diluted with its bulk of water; oxymuriatic acid is separated, passes into K, and dissolves the magnesia, which is kept suspended in the water by constant stirring. When it is required for use, as large a portion of it is drawn off into a copper containing water, and heated to the temperature of 170o of Fahrenheit, as will give the water a perceptible taste and as soon as it is drawn off, the two must be mixed together by means of a clean broom. The printed goods are then run over the wince into the copper, till the white is sufficiently clear, which requires only a few minutes, and immediately afterwards the goods are streamed in pure water to prevent the further action of the bleaching fluid.

CHEMISTRY AS A SCIENCE, Art. VI.

HYDROGEN.

HYDROGEN gas, the substance we are now to describe, for nothing is known of its base to which the term hydrogen strictly applies, is so named from a Greek word, sig nifying water-former. Hydrogen, in combination with oxygen, forming that fluid, and being always procured from it. By chemists it is considered as the distinguishing constituent element of water, which has now, for some time, been classed among compound substances.

The gas is thus procured:-put into the retort A, described in No. IV, Fig. 2, a quantity of iron filings.