•108 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
[August 6,1870. 
is this compound to which the ointment of mercurial 
nitrate owes its yellow colour. It is supposed that the 
discoloration of the officinal ointment occurs more parti¬ 
cularly when the oxidation of the fatty matter has not 
been sufficient, and that subsequently the avidity of these 
bodies robs the mercurial salts of their oxygen and re¬ 
duces them to the metallic state; but in the officinal oint¬ 
ment the greater part of the mercury no longer exists as 
normal nitrate, but chiefly as basic nitrate and mercurous 
or mercuric salts of some of the fatty acids either origi¬ 
nally existing in the fat or as products of its decomposi¬ 
tion. This is amply evidenced by employing a drying- 
oil, as the oils of cotton or flax-seed, in the preparation 
of the ointment, which of course, as will be seen, are en¬ 
tirely inadmissible for this purpose. If flax-seed oil, for 
instance, is heated with nitric acid alone, even until the' 
latter is entirely consumed, no separation will take place; 
but if to the heated oil the mercurial solution be added, 
a greenish-yellow agglutinated mass immediately sepa¬ 
rates, which adheres to the bottom of the vessel and the 
stirrer too tenaciously to admit of distribution, and more¬ 
over hardens on cooling to the consistence of lead plaster. 
Strong cold nitric acid has no apparent action on this 
substance ; neither have oil of turpentine, alcohol, ether, 
and carbon disulphide, when repeatedly treated with 
these solvents in succession; but chloroform dissolves 
the greater part of it, leaving a greyish, light, flocculent 
deposit, which agglutinates on the addition of alcohol. 
Cold strong nitric acid attacks this powerfully, forming 
a green solution containing abundance of mercuric oxide. 
At the same time a yellow oily substance separates, 
which completely dissolves in chloroform—also in ether, 
but slowly and imperfectly in alcohol—to an intense 
yellow colour, and saponifies with potassium hydrate to 
a deep red colour. The original resinous substance, as 
it separates from the supernatant oily liquid, is but 
faintly acted on by cold strong nitric acid; but the same 
acid, when hot, dissolves all but a yellow oil, which se¬ 
parates from the solution, and contains mercury in abun¬ 
dance, as the black precipitate with ammonium sulphide 
indicates. The first chloroformic solution of the resinous 
deposit, when evaporated, leaves a reddish-yellow var¬ 
nish-like residue, which is insoluble in water, but readily 
saponifies with potassium hydrate to a red solution, whilst 
a small quantity of mercurous oxide at the same time se¬ 
parates. By the addition of nitric acid to a solution of 
this soap, a yellow precipitate again occurs. 
The separation of this resinous deposit at the very 
outset of the operation, goes to show how easily the mer¬ 
curial nitrates are reduced by heat, or, more particularly, 
by the combined influence of temperature and the re¬ 
ducing property of the organic substances, even in the 
presence of a large excess of free nitric acid, which seems 
to indicate, in this instance at least, that the replacement 
of the hydrogen atom of the acid molecule through the 
mercurial atom, renders it more unstable in the presence 
of organic matter, and, therefore a more powerful oxi¬ 
dizer. 
The evolution of nitrogen dioxide during the solution 
of the resinous remnant, insoluble in chloroform would 
also indicate that the body contained either metallic 
mercury or the suboxide. This supports the supposition 
that the mercurous compounds are less stable than the 
mercuric under similar circumstances. It also affords 
incontrovertible evidence that in the officinal ointment 
the smallest portion of the mercury exists as nitrate, and 
that the greater portion can be present in an indefinite 
variety of forms. Therefore, the only form in which the 
metal should be combined is as mercuric nitrate, and the 
title should designate it accordingly. 
Secondly, a portion of the fatty substance which the 
formula demands cannot be obtained, unless the pharma¬ 
ceutist prepares it himself, because an officinal neat’s-foot 
oil does not exist in the market, hut a rank and disgust¬ 
ing semi-fluid grease, which possesses none of the officinal 
characteristics. But pure lard can always be readily ob¬ 
tained, and, since it furnishes an excellent ointment, 
should invariably be used. 
Thirdly, the manner of executing the officinal opera¬ 
tion is the very embodiment of failure. In this process 
it is of the utmost necessity to employ vessels of immense 
proportionate size. It is a point of great importance to 
retain the temperature of the heated fats within certain 
limits, which is an exceedingly difficult office to perform 
after a violent reaction has set in; and even with all 
these precautions the ointment may overflow or its colour 
be impaired from reduction of the metal by too great a 
heat. The production of a good ointment by this pro¬ 
cess is therefore a matter of chance, and depends upon 
circumstances that seem rather the good luck of the ope¬ 
rator than a well-defined pharmaceutical process. 
Now, all these difficulties can be readily overcome by 
an entire change in the operation itself, regardless of the 
component elements of the formula. The new process 
rests upon a scientific basis, whose characteristic feature 
pervades it in every detail, and which must therefore in¬ 
variably yield a uniform and definite result. Two pa¬ 
rallel operations, separate and distinct, unite their per¬ 
fect results to one complete and unchangeable whole. 
The formation of mercuric nitrate is effected with the re¬ 
quisite quantity of nitric acid, and the remainder is com¬ 
pletely consumed in the oxidation of the fats. This en¬ 
sures the ultimate existence of but one compound of mer¬ 
cury in the finished product, and that is, as the title 
implies, the mercuric nitrate. It likewise admits of the 
oxidation of the fatty matter to the utmost capacity of 
all the available nitric acid, so that when the last vestige 
of this has disappeared the mercurial solution can be 
mixed with tire nearly-cooled product without causing 
any further reaction. A very decided advantage of this 
process is that the enormously large vessels can be dis¬ 
pensed with. The nitric acid is added to the melted fat, 
and the heat continued until brisk ebullition sets in. 
This occurs mainly in the centre of the mixture, and 
without frothing. It is, however, of the utmost neces¬ 
sity not to disturb the liquids by stirring. If the re¬ 
action becomes too violent, the mixture must be removed 
a short time from the fire ; and if the action slackens too 
much, it must be replaced. Finally, when all the nitric 
acid has been decomposed, the temperature can be con¬ 
siderably raised without causing any further efferves¬ 
cence. The boiling then is analogous to the boiling of 
fatty matters in general. 
From the foregoing results the following formula is 
deduced 
Take of Mercury. 1| troy ounces. 
Nitric Acid, sp. gr. 1*42 .. 3^ „ 
Lard (pure) . 16| „ 
Dissolve the mercury in 900 grains of the nitric acid, 
with the aid of heat, and keep the solution gently warm 
to prevent crystallization before it is used. Melt the 
lard in a suitable vessel with a moderate heat; then add 
the remainder of the nitric acid, and continue the heat, 
without stirring the mixture, as long as moderate effer¬ 
vescence continues ; but if this becomes too violent, re¬ 
move the mixture from the fire, and only replace it when 
the action slackens too much. Finally, when efferves¬ 
cence ceases and the liquid only boils, even under an in¬ 
creased heat, remove the mixture from the fire altogether ; 
and when it begins to stiffen, add the mercurial solution, 
and mix thoroughly .—The Chicago Pharmacist. 
Prevention of “ Pitting ” in Smallpox. —As a 
means of preventing the disfigurement attending this 
disease, a writer in ‘ Union Medicale ’ recommends the 
paintkig of the pustules, as soon as the eruption appears, 
with tincture of iodine. The application should be con¬ 
tinued for five or six days. 
