282 SOLID PARTS OF ANIMALS. 



a yellow precipitate with diacetate of lead and nitrate of silver. 

 Acetate of lead and protochloride of tin occasion no precipitates. 



If we deprive the liquid which has been precipitated, by the 

 infusion of nut-galls, of its excess of tannin, by adding acetate of 

 lead, drop by drop, as long as a precipitate falls, and then eva- 

 porate the filtered liquor over the steam-bath, an acid extracti- 

 form matter remains, which contains lactate of ammonia. When 

 heated it gives out the smell of roast-meat. It is a mixture of 

 lactate of ammonia, and of a quantity of extract identical with 

 the portion left, when the matter dissolved by alcohol of 0-833 

 was digested in absolute alcohol. 



The aqueous extract remaining after the preceding treatment 

 with carbonates of ammonia and alcohol of 0-833, contains at 

 least four different extractive substances. If we dissolve the 

 mass in water, and then add caustic ammonia, and afterwards 

 acetate of barytes, a precipitate of subphosphate of bary tes falls, 

 coloured brown by organic matter. A similar calcareous phos- 

 phate is precipitated by lime-water. If we wash the precipitate, 

 and digest it in a stoppered phial with weak caustic ammonia, 

 a portion of the organic matter is extracted, and a brownish yel- 

 low solution is formed, which, being filtered and evaporated to 

 dryness, leaves a brownish yellow matter, having the characte- 

 ristic taste of the aqueous extract. The barytic phosphate, how- 

 ever, still retains a portion of organic matter in combination. 



The liquor from which this phosphate was precipitated, if it 

 contain a great excess of alkali, must be neutralized by acetic 

 acid. It is then to be completely precipitated by acetate of lead ; 

 saturating the acetic acid, as it becomes free, with ammonia. 

 The precipitate obtained is light and has a yellow colour. It is 

 to be collected on a filter, washed, mixed with water, and decom- 

 posed by sulphuretted hydrogen. The liquor thus treated must 

 be heated to allow the sulphuret of lead to precipitate. The 

 filtered liquor is brown, and this colour cannot be removed by 

 animal charcoal. It has an acid reaction, and contains a little 

 lactic and muriatic acids. We get rid of them by saturating 

 them with ammonia, evaporating to the consistence of a syrup, 

 and treating the matter with alcohol of 0*833. The ammonia- 

 cal salts are dissolved and the extractive matter remains. 



It is a brown matter, which becomes hard when dried, and is 

 not altered by exposure to the air. It has a strong and agree- 



