CHEMISTRY OF THE PTOMAINES. 217 



per cent.), crystallizes partly in cubes, and partly in long 

 needles which at first possess a bright lustre, but under the 

 desiccator soon effloresce and become opaque. The water 

 of crystallization is completely removed on standing over 

 sulphuric acid. It is very easily soluble, and melts at 188° 

 (Bocklisch). 



The PiCRATE, C5H„]Sr2.2CeH2(N02)30H, forms yellow 

 plates which are difficultly soluble in cold water. From 

 hot water it crystallizes in long prisms, which melt at 221° 

 with decomposition. It is insoluble in absolute alcohol 

 and can be recrystallized from hot dilute alcohol. 



Cadaverine hydrochloride combines with mercuric chlo- 

 ride, when the aqueous solutions of these two salts are 

 mixed in the molecular ratio of 1 to 4, to form CjHj^Nj. 

 2HC1.3HgCl2. This salt can be recrystallized from hot 

 water (Ladenbueg). When an excess of mercuric chlo- 

 ride is used the double salt has the composition CjHj^Nj. 

 2HC1.4HgCl2. This last salt melts at 216° (Ladenbueg) ; 

 at 214° (Bocklisch). It is difficultly soluble in cold 

 water ; from hot water it crystallizes in needles or plates 

 (Bocklisch). 



The Neutral Oxalate, C,Hj^]Sr2.H2C204-t-2H20, was 

 prepared by Bocklisch by adding a little less than the cal- 

 culated quantity of alcoholic oxalic acid to the cadaverine. 

 The precipitate may be recrystallized from hot dilute alco- 

 hol, when it is obtained in the form of needles, which melt 

 at about 160° and at the same time give off gas. 



The Acid Oxalate, C,II,^N2.2H2C20^-|-Il20, is made 

 by bringing the neutral salt into alcoholic oxalic acid. It 

 is soluble in hot dilute alcohol, and recrystallizes from it in 

 quadratic plates, sometimes in glistening needles. It melts 

 at 143° with decomposition. After it has been dried 

 over sulphuric acid, it loses, on being heated to 105°-110°, 

 one molecule of water (Bocklisch, Ber. 20, 1441). The 

 insolubility of these oxalates in absolute alcohol shows the 

 fallacy of Tamba's distinction between ptomaines and vege- 

 table alkaloids. (See page 186.) 



The DiBBNZOYL derivative, C,H,„(N'HCOC5H5)2, crys- 

 tallizes in long needles and plates, readily soluble in 



