July 22, 1871.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS 
65 
tion of one minim to the grain, or double the present 
officinal strength, would probably stand indefinitely, and 
this change of strength is, in the writer’s judgment, very 
desirable. The details of this percolation are given in 
the tables. In the management of this drug the weak 
percolates become overloaded with extract from time to 
time, but the alcohol can be easily recovered from them 
without much damage, as the glycerine takes care of the 
alkaloids and bitter principles. 
The writer has found no demand for fluid extract of 
colchicum root, and believes it to be a useless prepara¬ 
tion, while that of the seed is so commonly used, and a 
more uniform preparation. 
{To be continued.) 
THE THEORY OF DISINFECTANTS.* 
BY T. r. BLUNT, M.A., F.C.S. 
The light which has recently been thrown upon the 
nature of contagion and infection by the labours of 
Pasteur and others, the results of which have been ably 
summarized by the President of the British Association 
in his late inaugural address at Liverpool, seems to point 
the way to clearer and more comprehensive views than 
those commonly entertained at present regarding the 
operation of the substances known as disinfectants. 
These may be divided into tv r o classes :—1. Those 
which act by the oxidation and total destruction of the 
virus contained in infected matters, together with the 
foul gases which usually accompany it, and which are, 
in fact, nature’s danger-signals of its presence. 2. Those 
substances which do not possess the active chemical pro¬ 
perties of the first class, yet are proved by experience to 
have a similar power of arresting and checking the 
spread of infection. The latter are, for the most part, 
the more ancient and popular, having apparently in 
some cases been suggested by a just but unreasoning in¬ 
stinct. Thus w r e find that the use of sulphurous acid, 
as evolved from burning sulphur, dates even from 
Homeric days; while the burning of pitch and aromatic 
gums for disinfectant purposes has an origin at ffiast 
equally remote. 
An attempt will be made, in the course of the observa¬ 
tions which follow, to bring the operation of the large 
majority of the latter class under a general law 'which 
shall furnish us with an explanation of their true cha¬ 
racter. This is especially desirable, since it is to bo 
feared that, for want of such an explanation, many good 
and valuable disinfectants have been condemned by che¬ 
mists, on theoretical grounds, a 3 mere deodorizers,—not 
assailing the virus of infected substances, but rather 
masking their poisonous character by precipitating their 
offensive gases. An objection to this view at once meets 
us, in the utter disproportion between the volume of the 
gases to be fixed and the quantity of salt practically 
found sufficient for the object required, while it breaks 
down altogether when applied to such disinfectants as 
the new “chlor-alum” or chloride of aluminium of Mr. 
John Gamgee, or the well-known carbolic acid. Before 
endeavouring to supply a more probable theory, it may 
be well to remind you that the researches already men¬ 
tioned have established the fact that contagion and putre¬ 
faction, if -not actually identical, are processes so closely 
allied that they require exactly similar conditions; the 
latter appearing to consist of a kind of disease propa¬ 
gated from particle to particle of a decomposing stib- 
stance, and ending in its entire destruction. Hence it 
may be inferred with perfect safety, that any agent which 
arrests putrefaction is capable also of abolishing the 
properties of contagion and infection. 
This conclusion at once puts into our hands a valuable 
instrument of research; for wffiile it is difficult, and often 
_ * Read before the annual meeting of the Shropshire Scien¬ 
tific Branch of the British Medical Association. 
impossible, to investigate directly the disinfectant action 
of a substance, the inquiry being surrounded by innu¬ 
merable sources of error, the properties of an antiseptic 
are perfectly well defined and open to the clearest de¬ 
monstration. Thus, in the case of the tw-o bodies men¬ 
tioned above, carbolic acid and chloride of aluminium, 
the antiseptic action of the first is well known, and has 
long been usefully applied; while that of the latter is 
maintained in the most positive manner by its intro¬ 
ducer, Mr. John Gamgee, who certainly brings forward 
overwhelming proof of it in his recorded experiments 
upon meat and fish; and hence, on the grounds given, 
w 7 e are justified in regarding these substances as good 
and useful disinfectants. It may be stated, in passing, 
that the deodorizing power winch these and other similar 
bodies possess is probably due to their antiseptic action; 
the offensive gases of decomposition being sooner lost by 
diffusion, and their fresh production being entirely sus¬ 
pended. 
Let us now proceed to a consideration of the origin of 
the remarkable properties which w r e have described. 
This appears to have been traced with some degree of 
probability, in the case of carbolic acid, by Dr. Joseph 
Hirsch, the writer of an article which appeared in the 
Chemical News about the end of February, 1S69. He 
advances the bold and ingenious speculation, that the 
disinfectant action of that substance depends upon its 
power of coagulating albumen. He supposes that the 
acid finds its way into the minute organisms, which pro¬ 
pagate disease by diffusion through their investing mem¬ 
brane ; that it coagulates the albumen which they, in 
common with all germinal matter, contain as a necessary 
constituent; and thus practically destroys their vitality 
as perfectly as immersion in boiling water terminates 
that of an egg. 
In order to test the accuracy of the view thus enun¬ 
ciated, I selected a substance of which the albumen- 
coagulating power v 7 as well known, and examined it wnth 
regard to its antiseptic, and, therefore, disinfectant pro¬ 
perties. The substance chosen was nitro-muriatic acid, 
which has long been in use as a test for albumen in urine. 
The experiments were conducted as follows. 
a. Two samples of fresh healthy urine, passed at the 
the same time, each measuring about one ounce, were 
placed side by side. To one of them six drops of strong 
nitro-muriatic acid were added. In a few days, the un¬ 
acidified specimen w r as covered with a thick crust of 
mould; while that to which the acid had been added was 
unaltered, except by a slight darkening of colour and 
deposition of crystals of uric acid. 
b. Some fresh meat was pounded into an emulsion with 
wnitor,—the whole divided into two equal portions of 
about six drachms each. To one of them six drops of 
strong nitro-muriatic acid were added, as in the former 
case. In a day or two, the unacidified sample was quite 
putrid and offensive; while that to which the acid had 
been added retained the smell of fresh meat, and con¬ 
tinues to do so still, after the laps’e of nearly a month. 
I now 7 proceeded to test some of the salts commonly 
used as disinfectants, with respect to their possession of 
this powder of coagulating albumen. The examination 
was conducted thu3. One part of the salt to be tested 
was dissolved in one thousand parts of distilled water, 
and the solution w r as mixed thoroughly with the fresh 
white of egg. The salts examined w r ere iron-alum, 
sesquichloride of iron, common alum, chloride of zinc 
and nitrate of lead. Coagulation followed immediately 
in every instance. In one or two cases the dilution was 
carried much further,—one part of the salt to three or 
four thousand of w r ater. Here, too, coagulation followed 
in one or two seconds. 
It may be remarked, in passing, that the haemostatic 
action of the iron-salts is probably to be attributed in 
great measure to this faculty of coagulating albumen, 
exercised upon the serum of the blood. 
The attempt to obtain similar results from the sul- 
