September 3, 1870.] THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
197 
was of a different kind. It assimilated the water—the 
starch combined with the water, and at the same time 
divided itself, some of it forming- one and some the other 
product. Here, also, there was not, as far as my know¬ 
ledge goes, any ferment or any organized cells in the 
liquid. If they were present it was an accident, and 
was not essential to the change which took place. I am 
the more confident in saying that no ferment was there 
present, for we can get, and wo very often do get, pre¬ 
cisely the same formation of starch without any malt at 
all. If, instead of warming some of that starch with the 
infusion of malt, I had mixed it with a little—about 
five per cent.—of that strong sulphuric acid, and had 
heated it, it would have been dissolved almost like sugar 
in water. In fact, there are now in Germany, and also 
in England, manufactories in which starch is converted, 
by the action of dilute sulphuric acid, into grape-sugar, 
and the same change which we get by organic substances 
—that is the point—we also get by the action of this 
mineral acid. 
Another change of the same kind I may mention, es¬ 
pecially as the subject of it is in itself interesting. I 
have here a substance which people have been accused 
of making for the purpose of adulterating quinine. It is 
made from willow-bark, and is believed to possess febri¬ 
fuge qualities, so that there was some little excuse for 
what I have mentioned. This substance is called salicine, 
and when heated with dilute sulphuric acid, in the same 
way as the starch when so heated was converted into 
sugar and dextrine, this salicine breaks up in a way 
which I might compare with that in which some bodies 
are broken up by fermentation. 
Another case of the same kind is afforded by tannin, a 
substance extracted from gall-nuts, and which is present 
in oak and many other barks. It is used for combining 
with gelatine, which is the principal constituent in hides, 
to form leather. If we dissolve this tannin in water, 
and leave it in an open vessel, it will get mouldy; and 
if you examined it after some tune you would find none 
of it left. It would all disappear, just like sugar in the 
process of fermentation, and in place of it you would 
find, in that particular process, a body which you might 
easily crystallize out from the liquid, and which I have 
here; it is called gallic acid. It is a body resembling 
tannin in some respects, for instance, in the property 
of forming, in combination with iron, a dark substance, 
which is used in suspension in water, for writing-ink. 
But it will not do to form leather in combination with 
gelatine. If you left the tannin in an open vessel, it 
would decompose, and there would be left gallic acid, 
and some other material which was formed at the same 
time would have disappeared. By boiling tannin with 
dilute acid, we get the process performed more regularly. 
Upon boiling some tannin with dilute sulphuric acid, 
you would find that water would be taken up by it, 
the ta nnin would combine with water, and it would 
break up into sugar and gallic acid, the process being 
exactly like that which I mentioned in the case of 
salicine. There is a most direct analogy between the 
process of breaking up which sulphuric acid effects upon 
tannin and that of fermentation. I ought to say, when 
telling you of the decomposition of the tannin, that it is 
effected by little animal organisms present in the liquid, 
and it appears that they are the agents of the trans¬ 
formation. 
Then there are some other processes of considerable 
importance, from their occurrence in the animal economy 
—processes which I believe must be classed between 
those experiments which I showed you a little while ago 
and the process of fermentation,—I mean processes which 
occur in the operation of digestion. I have here a 
gelatinous solid, which contains a substance called 
pepsine, which was made by dissolving the inner lining 
of a pig’s stomach in diluted hydrochloric acid at about 
blood-heat. The inner lining of the stomach of that and 
similar animals is dissolved gradually, and that solution 
possesses the property of dissolving muscular fibre, 
white of egg, and other similar substances ; it is, in fact, 
artificial gastric juice, and it would, for instance, dis¬ 
solve that lump of gluten which I showed you just now 
—which looked something like india-rubber—and when 
this pepsine dissolves albumen by digestion, for the 
process is doubtless of the same kind as that which oc¬ 
curs in the animal economy, it does so by breaking it 
up into bodies which are no doubt simpler than itself, 
bodies which we do not know accurately and fully. 
They arc called peptones, for it is common enough to 
give names to bodies even before one knows them well. 
I do not know whether it is a good plan, but it is 
customary. These bodies are a good deal similar to 
those which are present in malt, and in such like mix¬ 
tures which have undergone vital changes. 
Then I will give you one or two other cases of similar 
processes. Here is a singularly beautiful acid, called 
hippuric acid, which decomposes with very great readi¬ 
ness if left in the liquids in which it is originally found. 
When that organic mixture is exposed to the air, it 
undergoes a process of putrefaction. The general ap¬ 
pearances which take place in the liquid while the sub¬ 
stance is decomposing would certainly be described by 
anybody as a putrefactive process, and there is formed, 
by its decomposition some of this other beautiful acid, 
called benzoic acid, because it was originally obtained 
from the fragrant gum benzoin. At the same time there 
are other products given off which decompose. Now, we 
can by mineral substances effect the same decomposition 
of that hippuric acid. A German chemist, to whom we 
owe many researches in these matters, showed, some 
years ago, that if you boiled hippuric acid with dilute 
sulphuric acid, it takes up water, and breaks up into ben¬ 
zoic acid, and this crystalline substance, called glycocol 
or sugar of glue. It got that name from the circum¬ 
stance that it was obtained originally from glue by a de¬ 
composing action, and it has a sweet taste. It has no 
analogy to sugar in its nature, but it has that superficial 
resemblance that it is rather sweet. 
This hippuric acid affords another case of a body which 
is broken up either by putrefaction, or by the action of 
dilute sulphuric acid. It affords a strong argument, and 
other cases I have adduced afford, like it, an argument 
that the action of these organic substances resembles the 
action of sulphuric acid. If we get the same change in 
several cases by the action of an organic body as by the 
action of a mineral body, the fact certainly goes some 
way towards showing that the two substances must be, 
in their mode of action, generally alike. There is an¬ 
other case, that of urea, which in contact with water 
forms a carbonate. That may be done by either class of 
re-agent. ~ 
There are, however, some chemical processes even 
simpler than these, and for that reason they are better 
known to us, which really may be studied -with advan¬ 
tage side by side with those I have mentioned, and they 
will, I think, afford us, on further consideration, a key 
to the explanation of these processes. I will only men¬ 
tion two. One is a process which is well known in its 
general features, and it is a process of breaking up truly 
analogous to those I have mentioned, but a perfectly 
simple breaking up of alcohol into two substances, both 
of them well known now, one being water, and the other 
ether. It is a process which consists in dividing the 
elements of alcohol in such a way as to get nothing- 
formed but these two products, though side by side with 
this change there are some secondary changes which do 
not belong to the process. This change is effected solely 
by the action of oil of vitriol or sulphuric acid. It has 
been long known, and it was a subject of wonder for 
some time that, if sulphuric acid is mixed with alcohol 
and heated, you can distil off some alcohol from the 
mixture in the form of these two products; then you 
may add some more alcohol, and if you distil that oft, it 
is also broken up into ether and water; then you may 
