36

DYEING AND CALICO PRINTING.

The composition of this substance does not differ very widely from that ofcerosic acid, the acid formed by the adtion of dry potash and lime on cerosine,which, according to Lewy, consists of—

C.8o-ii

H. 13-55

O ■■■ . 6 34

100-00

There can be little doubt that cotton-wax is identical with the “ resin "which, according to Persoz and others, is peculiar to cotton, and which issaid to protedt the filaments from the adtion of external agents. Dr. Schunckinclines to the belief that it is formed on the exterior of the fibres, and clothesthem with a thin waxy covering (like the coating of a similar material some-times found on leaves and fruit), and thus imparts to them their well-knownproperty of resisting water. If it be supposed to be contained solely in theinterior of the cells forming the fibres of cotton, it is difficult to conceive bywhat means any portion of it comes to be dissolved in the alkaline lye, inwhich, when pure, it is quite insoluble. Its solubility in alkalies is not pro-moted in any appreciable degree by admixture with the colouring matters ofcotton ; for on adding to it a quantity of either of the two colouring matters,and adting on the mixture with alkali, the colouring matter is simply dissolved,leaving the wax behind.

The quantity of cotton-wax obtained in the experiments was exceedinglysmall. It amounted to about 1 per cent of the weight of the brown precipitatethrown down by acid from the alkaline extradt. It is by no means certain,however, that this was the total quantity contained in the cotton.

Fatty Acid from Cotton.

This substance, when prepared in the manner above described, has theappearance of a white mass consisting of microscopic needles arranged inspheres. It fuses at 55-5 0 C., and solidifies again at 50-5° C. When heated onplatinum it melts, and then burns with a highly luminous flame. Heated in atube, it is volatilised, leaving hardly any residue and furnishing an oily sublimatewhich soon becomes solid. It dissolves readily in alcohol and ether. The alco-holic solution reddens litmus paper slightly. It dissolves in warm caustic potashand soda-lye, as well as in liquid ammonia; and the solutions froth on being boiled.The solution in potash yields, on cooling and standing, a quantity of crystal-line needles, while the solution in soda gives immediately a thick soap whichfills the whole liquid. The solution in ammonia deposits, on cooling, shiningcrystalline scales. The compound with soda is obtained in a state of purityby adding carbonate of soda to the alcoholic solution of the acid, evaporatingto dryness, treating the residue with boiling absolute alcohol, filtering, andevaporating. When this compound is dissolved in boiling water, and thesolution is allowed to cool, it is deposited again as a gelatinous mass, which,when examined under the microscope, is found to consist of small needles,arranged in star-shaped or fan-shaped masses. The watery solution giveswith the chlorides of barium and calcium white flocculent precipitates, withacetate of lead an abundant white precipitate, and with nitrate of silver awhite flocculent precipitate which becomes only slightly discoloured on