418 
PHARMACEUTICAL MEETING. 
were now, for the first time, shown to be otherwise. These were very important 
matters, and chemists should thank microscopists for having thus reminded them 
that they should apply the test of heat more carefully than they had done. He 
thought, however, that there were some misconceptions with regard to the 
general process of sublimation. Mr. Waddington appeared to have some diffi¬ 
culty in understanding how a substance could sublime and decompose at appa¬ 
rently the same temperature, and thought that what was true of a part should 
be true of the whole. That was a perfectly logical statement, no doubt, but 
temperature was not the only condition on which sublimation depended. Cam¬ 
phor sublimed at common temperatures, and therefore if a grain of that substance 
sublimed, why should not the whole bulk at the temperature of an ordinary 
room? So it would, if they gave it time ; that was the important consideration. 
Iodine sublimed at almost any temperature, and so did mercury ; solid water as 
well as liquid water volatilized. If a piece of ice were introduced into the 
vacuum of a barometer, all parts of the apparatus being kept much below the 
freezing-point, it would lose in bulk by volatilization. He had himself from 
time to time watched two or three ounces of naphthalin sublime on to the glass 
cover of the case in which it was placed, appearing in magnificent crystals, but 
it took seven years to do it. It seemed to him that alkaloids and such bodies 
required much time for complete sublimation, possibly because, among other 
reasons, in their ordinary conditions they were bad conductors of heat: it was 
easy to conceive of a fragment being only warm in the centre while it was char¬ 
ring on the outside, the intermediate part perhaps giving a sublimate. Then, 
too, he thought, that they must expect some bodies to sublime at most tempera¬ 
tures, and all volatile substances through a considerable range of temperature. 
Dr. Guy had attempted to fix the points at which alkaloids and other sub¬ 
stances sublimed, but he did not think much useful information, applicable 
as a diagnostic test, would be obtained by this method of research, because 
when they came to consider it, it would be found that there was no such thing 
as a definite subliming-point. They knew what the boiling-point was; that 
was fixed; but the subliming-point of a solid could be compared only to the 
evaporating-point of a liquid, and liquids evaporated through a great range of 
temperature; he did not see how they could fix the conditions of sublimation 
so as to afford any trustworthy test for the presence of a given object. Who 
would venture to assert that any particular degree of the thermometer were the 
subliming-point of mercury, camphor, naphthalin, or iodine? Lastly, when 
they remembered that many of these substances yielded sublimates which 
could not well be distinguished from each other, he thought they would come 
to the conclusion that much analytical aid could not be expected from this pro¬ 
cess of microscopic sublimation. But all must agree that these researches might 
be extended with great benefit to science, and that it would be well if they were 
taken up by more investigators. The subject was just one which, after such 
excellent introduction, could be well followed by gentlemen beginning their 
scientific career, and who, therefore, might have the necessary time at their dis¬ 
posal. Many substances now believed to be fixed would doubtless be found to 
be volatile, and new volatile products of non-volatile matters be discovered. 
ON A FALSE CINCHONA BALK OF INDIA. 
BY J. BROUGHTON, B.SC., F.C.S., 
CHEMIST TO THE GOVERNMENT CINCHONA PLANTATIONS OP THE MADRAS PRESIDENCY. 
Among the numerous indigenous febrifuges of South India, one of the most 
interesting is the bark of the Hymenodictyon excelsum (Wallich), or pundaroo. 
