1879.] 



On Liebreiclis Protagon in the Brain. 



155 



and then by nitration, the substance left undissolved by it was first of 

 ali dried between sheets of filtering paper in air, and afterwards over 

 sulphuric acid or phosphorus pentoxide. The resulting mass, which 

 had a snow-white colour, was reduced to powder, moistened with a 

 little water, and digested for many hours with alcohol heated to 45° C. 

 From the filtered liquid, if this be allowed to cool very gradually, the 

 protagon separates in the form of microscopic crystals, mostly arranged 

 in rosettes, the appearance and arrangement of which differs somewhat, 

 as Liebreich very exactly pointed out, according to the degree of con- 

 centration of the solution. The once crystallized protagon thus ob- 

 tained was collected on a filter, washed with ether, and dried first of 

 all in air and ultimately over P 2 5 . It was then recrystallized as 

 many times as required, the process always commencing by pulverizing 

 :and thoroughly shaking with cold ether. 



It appeared to us of special importance not merely to subject to 

 ultimate analysis several different samples of protagon, but specially 

 to subject to ultimate analysis protagon after the second crystalliza- 

 tion, and the same protagon after being recrystallized a third time. 



In our analyses the C and H were determined by combustions made 

 with lead chromate, with an abundance of reduced copper in the fore 

 part of the combustion tube. The determinations were made by 

 Dumas' method, the phosphorus was determined in some cases by 

 Carius's method, in others by fusion with sodium carbonate and salt- 

 petre. The results of every combustion, save two, in which unavoid- 

 able accidents occurred, are given below. 



The following are the results of the analyses : — 



1. Protagon twice recrystallized from ox brain. 

 0-288 grm. gave 0702 C0 2 and 0'284 H 3 0. 



0-355 „ 7 cub. ceutims. of X (at 0° C. and 760 millims.). 

 0-296 (treated by Carius's method) gave 0'0116 grm. of Mg 2 P 2 7 . 



2. Twice recrystallized protagon from ox, brain (same sample as 1). 

 0-306 grm. gave 0747 C0 2 and 0-2955 H 2 0. 



0-262 „ 6 cub. centims. of N (at 0° C. and 760 millims.). 

 0-3025 (treated by Carius's method) gave 0*012 grm. of Mg 2 P 2 7 . 



3. Ttuice crystallized protagon from ox brain (different sample from 

 1 and 2). 



0-284 grm. gave 0'691 grm. of 0O 2 and 0-270 grm. of H 2 0. 

 0-388 „ 8 cub. centims. of X at 0° C. and 760 millims. 

 0-782 „ 0-0291 grm. of Mg 2 P 2 7 . 



4. Twice crystallized, protagon from ox brain (same sample as 3). 



0-2968 grm. gave 0-722 C0 3 and 0-288 grm. of H 2 0. 

 0-5368 „ 0-02 grm. of Mg 2 P 2 7 . 



