CHEMISTRY OF THE PTOMAINES. "2 1 7 



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

 needles \vliich at first possess a bright lustre, hut under the 

 desiccator soon effloresce and become opaque. The water 

 of crystallization is completely removed on standing over 

 sul|)huric acid. It is very easily soluble, and melts at 188 

 (BoCKLiscir). 



The PICRATE, C ft H, 4 tf 2 .2C 6 H 2 (NO 2 ) 3 OH, forms yellow 

 plates which arc 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 recry stall ized from hot dilute alcohol. 



( 'adaveriue 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 C 5 H 14 N 2 . 

 2HC1.3IIir< '1... This salt can be rccrystallized from hot 

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

 ride is used the double salt has the composition C 5 H U N 2 . 

 2HC1.4HgCl 2 . This last salt melts at 216 (LADENBURG) ; 

 at 214 (BOTKLISCH). It is difficultly soluble in cold 

 water ; from hot water it crystallizes in needles or plates 



The NEUTRAL OXALATE, C,H 14 N 2 .H 2 C 2 O 4 +2H 2 O, 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 reerystallized from hot dilute alco- 

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

 at about 160 and at the same time give oft' ^as. 



The Ann OXALATE, O S H 14 N 2 .2H 2 C 2 O 4 +H 2 O, is made 

 by hrimrmi: the neutral salt into alcoholic oxalic acid. It 

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

 quadratic plates, sometimes in ^listeninjr needles. It melts 

 at 143 with decomposition. After it has been dried 

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

 one" i nolecule of water (BocKLiseii, Her. 20, 1441). The 

 insolubility of these oxalates in absolute alcohol shows the 

 fallacy of TAMBA'S distinction between ptoma'ines and vege- 

 table alkaloids. (See pajso 186.) 



The'DiBENZOYL derivative, C S H 10 (NHCOC 6 H 5 ) 2 , crys- 

 tallizes in long needles and plates, readily soluble in 



