152 BASIC BODIES. 



of copper- ffly cine was obtained by Boussingault, and found to be 

 represented by the formula C 4 H 4 NO 3 .CuO ; Horsford found 1 

 atom of water, in this compound which crystallised in brilliant blue 

 needles. Similarly to the hydrated oxide of copper, the hydrated 

 oxide of lead, and oxide of silver, may be dissolved in an aqueous 

 solution of pure glycine, and the compound after being precipitated 

 by the addition of alcohol, may be obtained in a crystalline form. 

 The lead-compound crystallises in prisms, the silver-compound in 

 wart-like masses. 



There is much regarding these compounds that still remains to 

 be investigated ; we have, however, entered more fully into the 

 subject of their composition than we should otherwise have 

 done, because it is on this point that we must form our judgment 

 respecting the constitution of glycine, and decide in favour of one 

 or the other of the above hypotheses. 



Preparation. Glycine has not yet been found in an isolated state 

 in the animal body : there is, however, reason for believing that this 

 substance is contained preformed as an adjunct in certain known 

 animal acids ; moreover, the relations of this body towards acids, 

 bases, and salts, (which we have already described,) support this 

 view ; while, in many cases with which we shall become acquainted 

 as we proceed, it is more than probable that glyciue is formed on the 

 separation of the acid from its proper adjunct, as glycerine is pro- 

 duced in the saponification of the hypothetical oxide of lipyl. As 

 instances, we may mention hippuric and glycocholic acids ; and 

 when we treat of these acids, we shall enter into the physiological 

 relations and the genesis of glycine. 



It has long been known that glycine is a product of the decom- 

 position of animal substances, especially of gelatin, by the action 

 of concentrated mineral acids or caustic alkalies. The following is 

 the best method of obtaining it from gelatin. If the gelatin be 

 boiled with a strong solution of potash till ammonia ceases to be 

 developed, it becomes entirely decomposed into a mixture of 4 

 parts of glycine and 1 of leucine ; the fluid neutralised with sulphuric 

 acid is evaporated to dryness, and the residue extracted with spirit 

 of wine which dissolves both the glycine and the leucine ; the glycine 

 as being the least soluble in alcohol, crystallises first, while the 

 leucine subsequently crystallises; by recrystallisation and treat- 

 ment with a little animal charcoal, the glycine can be obtained per- 

 fectly pure. 



The method of obtaining glycine from hippuric acid is even 

 simpler ; for if 1 part of this acid be boiled for half an hour with 



