THE TECHNOLOGIST. [Dec. 1, 1864. 



200 ON CHEMISTRY APPLIED TO THE ARTS. 



in water and alcohol, combining easily with hydrochloric, hydrobromic, 

 benzoic, tartaric, &c, acids, forming neutral compounds. Diluted nitric 

 acid converts it into glyceric acid ; concentrated nitric acid into nitro- 

 glycerine, or a substance exploding with violence by percussion, which 

 has caused it to be proposed as a substitute for fulminating mercury, by 

 its discoverer, Professor Sobrero. The application in medicine of 

 glycerine has been greatly extended by its highly hygrometric properties. 

 Thus, bandages moistened with glycerine remain constantly moist, 

 because the glycerine attracts moisture from the air as fast as it is lost 

 by evaporation. It has also been found eminently useful in diseases of 

 the eye and ear. Glycerine boils at 527 deg., but when distilled is 

 partly decomposed into a peculiar oily fluid, of a noxious odour, called 

 acroleine. M. Bertholet has succeeded, by fermentation, in converting 

 glycerine into alcohol. Again, Mr. George Wilson, F.R.S., the talented 

 director of Price's Patent Candle Company, has applied glycerine with 

 great success to the preservation of vegetable and animal substances. 

 Another useful employment of glycerine is its substitution for water in 

 gasometers, where the evaporation of the latter is a source of serious 

 loss. Its addition to a soap solution increases the facility of forming 

 soap bubbles to an extraordinary degree. In fact, by its aid, bubbles of 

 seven or eight inches diameter can be produced, exhibiting most 

 beautiful purple and green colours, the beauty of which is greatly 

 enhanced when illuminated by the electric light. To prepare this 

 peculiar soap solution the following proportions are stated to be 

 employed : — Distilled water, 5 ounces ; soap, £ of a dram ; glycerine, 

 2 drams. 



The extraction of the fatty matters of animals from the tissues en- 

 veloping them is a simple operation. The old process of doing this, 

 technically called " rendering," consisted in introducing the suet into 

 large iron pans and applying heat, which caused the fatty matters, by 

 their expansion, to burst the cells confining them, and to rise to the top 

 of the contents of the boiler, which were left to stand for a few hours, 

 and the liquid fat was theu run off. The organic tissues remaining with 

 a certain amount of fat at the bottom of the boilers were removed, and 

 subjected to pressure so as to separate the rest of the fat, the organic 

 tissues remaining behind being sold under the name of " greaves," for 

 feeding dogs, &c. As this operation gives rise to noxious vapours, 

 causing thereby great annoyance, other methods have been generally 

 adopted. For instance, Mr. D'Arcet's, the leading feature of which is, to 

 place in a boiler say 350 lbs. of suet with 150 lbs. of water and 15 lbs. of 

 sulphuric acid, carrying the whole to the boil for some hours, when the 

 sulphuric acid dissolves the organic matters and liberates the fatty ones, 

 which are then easily separated from the aqueous fluid. Mr. Evrard's 

 process appears preferable. He boils the fatty matters with a weak 

 solution of alkali ; or, in other words, he uses 300 lbs. of suet with half 

 a pound of caustic soda dissolved in twenty gallons of water, carrying the 



