ABQININ. 441 



The picrate, CS.^^p^.CSLjiip. , was prepared by Schulze and 

 Steiger {Z. P. C, 11, 43). 



Arginin copper nitrate, (CsHj^NPj)^ .Cu(N03)2 + S^HjO, was 

 obtained by boiling the nitrate with copper carbonate or hydrate. 

 Hedin,' Lawrow,'' as well as Schulze^ obtain the salt with only three 

 molecules of water, possibly because of loss of same by efflorescence. 

 This takes place slowly when the salt is kept in a desiccator. When 

 crystallized from hot water it forms roundish aggregates of dark 

 blue needles or pointed prisms. Impure solutions are difficult to 

 crystallize. It reacts alkaline and is soluble in 95.5 parts of water 

 at 13°. It melts at 112°- 114° but when dehydrated it melts 

 with decomposition at 232°- 234°. 



The copper sulphate, (C5Hj^N^02)2.CuSO^+ 5 JHjjO, was obtained 

 by boiling the sulphate withcupric hydrate. It melts at about 110° 

 and loses all the water of crystallization at 150° and decomposes at 

 170°. The dehydrated salt decomposes at 235°- 238°. 



The acid silver nitrate compound, CgHj^N^O^. HNOj + AgNOj, 

 on slow evaporation of its aqueous solution forms long colorless 

 needle-shaped prisms usually grouped in bundles. From hot satu- 

 rated solution it separates in opaque stellate masses of long, very 

 thin needles. Its solution which is very slightly acid is not reduced 

 on heating. It is soluble in 7.27 parts of water at 16° ; is insolu- 

 ble in alcohol and in ether, and is dextro-rotatory. It melts with 

 decomposition at 176°- 183°. 



The basic silver nitrate compound,* CjHj^N^O^.AgNOj -|- JHjO, 

 forms rosette or wart-like aggregates of short, colorless, transparent 

 prisms. Its solution reacts alkaline ; is easily reduced by light and 

 by heating. At 16° it dissolves in 88.7 parts of water (81 parts, 

 Hedin) ; is easily soluble in hot water. It is insoluble in alcohol and 

 in ether. It decomposes at 164°. This salt has been used as a 

 means of separation (Hedin). 



Arginin-silver,' CjHjjAgjN^Oj.HjjO, is obtained as a snow-white 

 cheesy precipitate when sodium hydrate is added carefully to the 

 acid silver nitrate compound. It is usually mixed with the similar 

 body containing three atoms of silver. The compound takes up 

 carbonic acid ; when powdered is markedly electric and darkens on 

 exposure to light. The moist powder when heated rapidly becomes 

 black. It is very difficultly soluble in water (1 in 28,571) ; easily 

 soluble in acids and in ammonia. 



A mercuric chlorid compound forms when this salt is added to a 

 solution of arginin. The voluminous, white, amorphous precipitate is 

 soluble in acids, and in hot water. When purified it becomes very 



' Zeits. physiol. Ohem., 20, 191. 



*Zeits. physiol. Ghem., 28, 392. 



3 Zeits. physiol. Ohem., 11 ; 52; 29, 331 ; 33, 561 ; 34, 138. 



'ZkUs. physiol. Ghem,, 20, 188 ; 21, 156 ; 27, 200. 



^ Zeits. physiol. Ghem., 22, 194 ; 27, 202. 



