ON SPIRIT OP NITROUS ETHER AND NITRITE OF SODA. 
9 
In the year 1839 the Edinburgh College also gave a process for the prepa¬ 
ration of nitrous ether, but simply as a preliminary step in the manufacture of 
spirit of nitrous ether. The method directed is to add by degrees, through a 
safety tube in a matrass, 7 fl. oz. of nitric acid, of 1*5 specific gravity, to 15 fl. 
oz. of rectified spirit, taking care that the action is not too violent, and that the 
receiver be kept cooled. The ether thus obtained is purified from acid by a 
little milk of lime, and from water and spirit by a concentrated solution of 
chloride of calcium (muriate of lime). The product (“pure hyponitrous ether”) 
thus obtained should have a density *899. This is then mixed with four times 
its volume of rectified spirit (so that the mixture would contain 20 per cent, of 
nitrous ether) • and the resulting spirit of nitrous ether is stated to have the 
specific gravity -847. This can hardly be correct, as the density of rectified 
spirit is -838, and the mean of the volumes given above will yield a result of 
•850. The gravity stated by the Edinburgh College would therefore entail an 
increase of volume on admixture which is not probable. The test given for the 
strength of spiritus setheris nitrici is that, “ when agitated with twice its volume 
of concentrated solution* of muriate of lime (chloride of calcium) 12 per cent, 
of ether slowly separates.” Now as the proportion of ether added to the 
spirit was 20 per cent., it is evident that 8 per cent, is held in solution by the 
mixture of spirit and chloride of calcium. The last Dublin Pharmacopoeia con¬ 
tained a process of a similar kind ; that is, forming a nitrous ether by the action 
of nitric acid on spirit, purifying the product by ammonia, and mixing it with 
10-5 volumes of rectified spirit, or with more than 2-5 times the quantity used 
by the Edinburgh College, maldng the product, of course, less than half the 
strength as regards the ether. 
The spirit of nitrous ether met with in commerce I have never found to yield 
any ether by the chloride of calcium test, nor have I ever heard of any which 
did. It could not therefore contain more than 8 per cent, of ether, that being 
the point at which the test will begin to indicate. In the last process of the 
London College for 1851 the gravity of the product (obtained by the distillation 
of nitric acid with rectified spirit), is stated as below that of the spirit used, 
namely *834, rectified spirit being -838, which can only be accounted for as an 
increase in the percentage of alcohol by the slow distillation. Lhe amount 
of nitrous ether present here must have been very small. Such then was the 
position of this manufacture, as far as regards officinal preparation, up to the 
time of the issue of the British Pharmacopceia. 
The original formula suggested by the Dublin Pharmacopceia Committee, 
and handed to me, as Consulting Pharmaceutic Chemist to the London and 
Edinburgh Committees, for trial, was as follows ;—“ 6 oz. of nitrate of soda, 
200 grs. of charcoal in very fine powder, oz. of sulphuric acid, 25 fl. oz. 
of rectified spirit. Mix the nitrate of soda with the charcoal, both in fine 
powder, and deflagrate the mixture in small and successive portions in a Hessian 
crucible raised to a low red heat. Then increase the temperature to produce 
perfect liquefaction, pour out the salt on a clean flag, and when cool reduce it 
to powder! Place it in a mattrass connected with a condenser, and pour on 
the spirit and acid previously mixed. Distil over 20 fl. oz. Specific gravity 
•835.” By experiment, deflagrating at as low a heat as possible, this yielded 
a product having a specific gravity -853, and giving by the chloride of calcium 
test 8 measures of ether per cent, separated, equal therefore to 16 per cent, 
really present, or 53 per cent, of nitrite of soda in the salt employed. 
This formula was then altered by the committees to that which now stands 
in the Pharmacopoeia, namely, 5 oz. nitrite of soda, 4 fl. oz. of sulphuric acid, 
~# This should bo “saturated,” as otherwise the test is most uncertain. This can only be 
ensured by always having undissolved crystals present in the solution employed, the point 
of saturation varying much with temperature. 
