2S4 CHEMICAL HISTORY OF THE GRATIOLA. 
ing, it acquires a purple color; the solution does not turn 
green when mixed with water, but it makes it rather cloudy 
and becomes discolored. 
Allow me, in connexion with this reaction, to offer a few 
reflections on the red color many bodies assume under the 
influence of concentrated sulphuric acid. It is sometime 
since M. Raspail pointed out, as a property characteristic of 
sugar, the power that substance possessed of developing a 
beautiful red color, when, after being mixed with albumen 
or oil, it is submitted to the action of concentrated sulphuric 
acid. More recently still, M. Pettenkofer observed, that 
when, in this experiment, you substitute biline for the albu- 
men or oil, the red color still appears. As early as in 1838, 
the first of these two chemists, speaking of the red color 
salicine always assumes when in contact with sulphuric 
acid, gave this opinion, that salicine might perhaps be 
merely a combination of sugar, and a principle which he 
denominated resineux, and which in this case might 
answer the purpose of exciting the characteristic reaction of 
sugar. Since that time, distinguished chemists have added 
their authority to the opinion of M. Raspail; for, in 1839, 
M. Liebig was led to consider salicine as a combination of 
grape sugar and saliretine. More recently, M. Piria was 
induced, in his turn, after a series of very remarkable expe- 
riments, to consider the same body (salicine,) as a combina- 
tion of sugar with another substance, discovered by him- 
self, and to which he gave the name of saligenine. As we 
see, then, let the constitution of salicine be what it may, 
chemists always agree that sugar is one of its elements, and 
the opinion of M. Raspail is entirely confirmed. 
Passing, then, to digitaline and gratioline, which also as- 
sume a beautiful red color when in contact with concentra- 
ted sulphuric acid ; recollecting that these bodies, like 
salicine, are neutral substances, would it not be right to 
presume that sugar enters also into their constitution ? I 
knowthat this question can only be resolved when we welt 
