324 CHEMISTRY OF THE PTOMAINS. 



nitric acid, then treated with an equal volume of a saturated solution 

 of potassium hydrate, and the whole concentrated on a water-bath 

 (this compound is not decomposed below 130°). On being heated 

 the mixture becomes yellowish-brown, and emits a peculiar aromatic 

 odor. On cooling the tyrotoxicon compound forms in beautiful, six- 

 sided plates along with the prisms of potassium nitrate. 



With equal parts of sulphuric and carbolic acids, pure tyrotoxicon 

 gives a green coloration, but in whey the color varies from yellow 

 to orange-red. This color reaction may be used as a preliminary 

 test in examining milk for tyrotoxicon. It is best carried out as 

 follows : Place on a clean porcelain surface two or three drops each 

 of pure carbolic and sulphuric acids. Then add a few drops of the 

 aqueous solution of the residue left after the spontaneous evaporation 

 of the ether. If tyrotoxicon be present, a yellow to orange-red 

 coloration will be produced. This test is to be regarded only as a 

 preliminary one, for the coloration may be due to the presence of a 

 nitrate or nitrite, or, as Huston and Weber have shown, to butyric 

 acid. The tyrotoxicon must be converted into the potassium com- 

 pound and purified before the absence of nitrate or nitrite can be 

 positively demonstrated. Moreover, the physiological test should 

 always be made in testing for this poison. 



With platinum chlorid in alcoholic solution tyrotoxicon forms a 

 compound which explodes with great violence at the temperature of 

 the water-bath. This also corresponds with the compound of plat- 

 inum chlorid and diazobenzol. It should be borne in mind, how- 

 ever, that organic peroxids may behave in a similar manner. 



Pure tyrotoxicon is insoluble in ether, and its extraction from 

 alkaline solutions by this solvent is due to the presence of foreign 

 matter with which the poison is taken up by the ether. 



The physiological action of this ptomaiin has been discussed in a 

 preceding chapter. 



Mydalein {ftudaXioz, putrid) is a poisonous base obtained in 1885 

 from putrefying cadaveric organs, liver, spleen, etc. (Brieger, II., 31, 

 48). Though it is apparently present on about the seventh day, it 

 is unobtainable until about the third or fourth week. The method 

 for its separation from the accompanying bases is given under saprin 

 (page 278). It is liable to occur in the mercuric chlorid filtrate, as 

 well as in the precipitate, inasmuch as the double salt is insoluble 

 only in perfectly absolute alcohol. In order to purify the platino- 

 chlorid obtained as on page 279, it is repeatedly recrystallized from 

 a very small quantity of lukewarm water. This base has not been 

 isolated in sufficient quantity to permit of a complete determination 

 of its composition. It is probably a diamin, containing four or five 

 carbon atoms, and hence is nearly related to some of the diamins 

 already described. 



