594 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



colored. But attention is particularly called to its substitu- 

 tion for tin for boxes for packing aniline colors, it being far 

 less expensive when manufactured from a cheap paper adapted 

 to this use, and easily made into box-like jiouches accurately 

 litted into light wooden boxes with smooth interiors, the 

 parchment box lid being fastened by a tin hoop, and the 

 Avooden one nailed. Such boxes are not only perfectly tight, 

 but not liable to be cracked or burst open by rough hand- 

 ling in carrying, as experience shows to occur with tin boxes. 

 25 (7,1 873, 98. 



PREPAEATIOX OF GELATOE. 



The high price of fine gelatine induced Hewze to attempt 

 the preparation of a cheaper and equally good article. He 

 l)egan with a brown, almost black, glue, of poor quality, ob- 

 tahied as a secondary product in the manufacture of neat's- 

 foot oil, and made by digesting feet with steam, with ad- 

 hering hair, after removal of the hoofs and leg bones, under 

 the pressure of three atmospheres, for three hours ; then al- 

 lowing the liquid to stand for half an hour, in order that the 

 fat might collect on the top, and next drawing off the strong- 

 ly ammoniacal solution of glue, straining, and evaporating in 

 a steam-bath to a friable, black mass. Attempts to bleach 

 this with sulphurous acid, and sulphite of soda and hydro- 

 chloride acid, were entirely unsuccessful, and would have 

 been impracticable on a large scale. Investigations of the 

 cause of the dark color were next made. The presence of 

 sulphur and considerable quantity of ammonia salts, indicated 

 that the energetic and prolonged action of the steam had af- 

 fected both the cartilaginous matter and the hair, and had 

 been the cause of the darkenins;. In order to reduce the de- 

 composition of the glue and the formation of ammonia to a 

 minimum, the process w^as so modified as to draw off the 

 liquid accumulated in the digester every hour, instead of 

 every third hour; and after it had remained at rest until all 

 the fat had collected, and had been removed, a mixture of 

 fresh charcoal and twenty-five per cent, of bone-black (about 

 equal to four per cent, of glue in solution) was added, and 

 the whole allowed to remain over night, to free it completely 

 from ammonia. Next morning it was warmed to about 68"^ 

 to 78, until the gelatine was melted, strained, and evapo- 



