82 M. C. Lea on Reactions of Gelatine. 
the expectation of colored combinations, whereas in the case I 
am about to mention, the precipitant is colorless, and the pro- 
duction of a marked color seems to point to a more complete 
his red coloration seems to require a certain amount of time 
for its production, which cannot be replaced by heat. If a piece 
_ of gelatine be immersed in the solution of protonitrate and boil 
for some minutes it is dissolved but the solution thus obtained 
is not red, but yellowish. 
t 
oyed., 
weak, as for example, if the gelatine constitutes only one half of — 
one per cent of the mixed liquids, the limit of the delicacy of 
the test is reached. Such a solution, by standing twenty-four 
hours, exhibits a light but distinct pink color. Alough this 
delicacy is not what may esired, still, colloid organic sub- 
acid, and then a moderate heat was ea ge for a sufficiently long 
i id when cold. It was then 
Philadelphia, May 12, 1865, 
