276 CHEMISTRY OF THE PTOMAINS. 



tallized from hot water (Ladenburg). When an excess of mercuric 

 chlorid is used the double salt has the composition C5Hj^N2.2HCl. 

 4HgCl2. This last salt melts at 216° (Ladenburg) ; at 214" (Bock- 

 lisch). It is difficultly soluble in cold water ; easily in hot water at 

 21° (1-32.5, Grulewitsch) ; from hot water it crystallizes in needles 

 or plates (Bocklisch). On heating even on the water-bath it loses 

 weight. At 125°-135° it loses 18.33 per cent, of its weight, 

 due to volatilization of mercuric chlorid (Gulewitsch). As pointed 

 out by Brieger, it is quite probable that other mercuric compounds 

 exist than those mentioned. Gulewitsch (1894) showed inter- 

 esting polymorphism of the mercury salts of cadaverin. He in- 

 clined to the belief that it may form compounds with more than 

 three or four molecules of mercuric chlorid. On heating mercuric 

 chlorid is given off, and hence the varieties in form. This variation 

 in form is, therefore, not necessarily due to impurities. When first 

 obtained the cadaverin mercurochlorid forms warty aggregates of 

 dark-brown prisms with pointed ends. By repeated recrystaUization 

 from water it eventually forms single or stellate rhombic plates, and 

 on further crystallization very thin, elongated, six-sided, or triangu- 

 lar plates result. 



The neutral oxalate, CjHj^Nj.HjCjO^ -f- 2H2O, was prepared by 

 Bocklisch by adding a little less than the calculated quantity of al- 

 coholic oxalic acid to the cadaverin. The precipitate may be re- 

 crystallized from hot dilute alcohol, 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, C5Hj^N2.2HjC,0^ -|- H^O, 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 in- 

 solubility of these oxalates in absolute alcohol shows the fallacy of 

 Tamba's distinction between ptomains and vegetable alkaloids. 



The dibenzoyl-derivative, CjHij(NHCOC5H5)2, crystallizes in long 

 or small needles and plates, readily soluble in alcohol, difficultly so 

 in ether, and insoluble in water ; hence the alcoholic solution can 

 be precipitated by addition of water or ether (separation from the 

 putrescin compound, see page 266). It melts at 129°— 130° ; at 

 130.5°-131.5° (Gulewitsch). It is not changed by boiling with 

 dilute acids and alkalis ; but boiling with concentrated hydrochloric 

 or sulphuric acid for a long time finally breaks it up. 



Neuridin, CjHj^Nj, was the first diamin isolated from animal tis- 

 sues (Brieger, 1883). It is one of the most common products of 

 putrefaction, and as such has been obtained by Brieger from putrid 



