ON THE CHEMICAL PROCESSES AND PREPARATIONS. 
415 
This method of effecting the combination of weak vegetable acids or acid salts 
with metallic oxides might have been followed with advantage in other cases, 
where much less efficient methods have been adopted. Thus, for instance, 
potassio-tartrate of iron, which is now called— 
Ferrum tartaratum , is directed to be made by heating the cream of tartar 
and oxide of iron in the presence of a large quantity of water, which is un¬ 
favourable to the combination of the metallic oxide with the acid salt. The 
process given for this preparation is also defective in ordering the solution in its 
very dilute state, as first produced, to be poured on to porcelain or glass plates, 
to be dried in scales. This mode of operating would be practically impossible. 
Ferri et ammonia citras .—The process for this preparation is subject to the 
same objections that attach to the preceding. There is too much water present 
when the combination is effected, and the solution, if formed as directed, would 
be in too dilute a state to be spread on glass or porcelain for scaling. 
Ferri et quinia citras .—I have not yet fairly tried this process, but I do not 
think it will yield the pretty salt which has become so firmly established in 
medical practice. 
I must now say a few words with reference to a preparation about which 
there has been a good deal of discussion lately in the Medical and Pharmaceu¬ 
tical Journals. I allude to the popular medicine called “ Sweet Spirit of Nitre.” 
There are great differences in the strength and quality of this medicine as met 
with in various pharmaceutical establishments, and some discredit has been 
thrown upon those who make it, and sell it, on account of this difference in 
quality. But I think it has pretty clearly appeared from the discussion of the 
subject, that the process given in the Pharmacopoeia has been as much at fault 
as those who have had to apply the process. Spiritus SEtheris JVitrici, made 
according to the process of the London Pharmacopoeia, might contain any quan¬ 
tity from a mere trace up to probably seven or eight per cent, of nitrous ether, 
according to the quantity of the ingredients operated upon in the process, the 
form of the apparatus, and the temperature applied in effecting the distillation. 
We have all been agreed and have long been aware that the process of the 
London Pharmacopoeia was liable to yield very variable results according to the 
mode of applying it, yet under the most favourable circumstances it has yielded 
a sweet spirit of nitre which the public, who are great consumers of it, have 
generally approved of. We have been fully aware of the defects in the processes 
hitherto used, and were given to understand that the British Pharmacopoeia 
would supply us with a new and greatly improved process. This new process 
is now before us. It consists in distilling a mixture of spirit of wine and oil of 
vitriol with nitrite of soda. The process, I have no doubt, would be a very good 
one if we had the means of carrying it out as intended ; but we are met at once 
with a difficulty, which is that nitrite of soda is not a commercial article. This 
difficulty, however, is met in the Pharmacopoeia by a process being supplied for 
the preparation of nitrite of soda. Unfortunately the process given for the 
preparation of nitrite of soda does not yield the product we require. I have 
tried the process myself, and have obtained samples of the so-called nitrite of 
soda made by the Pharmacopoeia process from several manufacturing chemists of 
the highest reputation, and in every instance I have found it to consist princi¬ 
pally of nitrate of soda, with a good deal of carbonate and a very little nitrite. It 
is a mistake to call this salt nitrite of soda, or to expect that the process given will 
yield a product having the composition represented by the formula (NaO ,N0 3 ), 
which is the formula given in the Pharmacopoeia. The nitrite of soda produced 
by the process of the British Pharmacopoeia will be a variable product, and the 
sweet spirit of nitre produced from it is not likely therefore to be uniform in 
composition or quality. This process for making Spiritus JEtheris Nitrosi is in 
operation before you, and you will have an opportunity of examining the pro- 
