ON THE preparation OF SPIRIT OF NITROUS ETHER. 
51 ^ 
Finding that of all the reducing agents tried, copper was that which acted 
in the most satisfactory manner, I returned to it, and endeavoured to over¬ 
come the objections that had presented themselves to its use. My object 
was not to produce pure nitrous ether, but good sweet spirit of nitre, and 
therefore the quantity of spirit required for this purpose was used. I found 
that in distilling a mixture of nitric acid and spirit in contact with copper, 
if the proportion of spirit to the acid was more than one to five by volume, 
the copper was but slightly acted upon; and here, as in the other cases 
noticed, the formation of nitrous ether did not take place to any appreciable 
extent until the proportion of acid to spirit was reduced to about one 
volume to four. The process then proceeded with great regularity, the pro¬ 
portion of ether in the distillate increasing as the liquid in the retort became 
more highly charged with nitric acid; but it was only during one short period 
of the process that the best result occurred, and with this exception the dis¬ 
tillation yielded little else than pure spirit. In endeavouring to equalize the 
action and difiuse it through the entire process I tried the elfect of adding a 
portion of sulphuric acid to the other ingredients, and in this way I com¬ 
pletely accomplished the object. 
After a great many trials, in which the ingredients were used in different 
proportions, I adopted the following process as one in every way suited for 
the production of spirit of nitrous ether, equal in strength and similar in com¬ 
position to that described in the British Pharmacopoeia:— 
Take of Nitric Acid, sp. gr. 1'42 .... 3 fluid ounces. 
Sulphuric Acid, sp. gr. 1'843 . . 2 fluid ounces. 
Copper, in fine wire (about No. 25) 2 ounces. 
Bectified Spirit.3 pints. 
To one pint of the spirit add gradually the sulphuric acid, stirring them 
together ; then add, in the same way, 2^ fluid ounces of the nitric acid. Put 
the mixture into a retort or other suitable apparatus, in which the copper has 
been introduced, and to which a thermometer is fitted. Attach now an effi¬ 
cient condenser, and applying a gentle heat, let the spirit distil at a tempera¬ 
ture commencing at 170° Fahr., and rising to 175°, but not exceeding 180°, 
until 12 fluid ounces have passed over and been collected in a bottle kept 
cool, if necessary with ice-cold water; then withdraw the heat, and having 
allowed the contents of the retort to cool, introduce the remaining half-ounce 
of nitric acid, and resume the distillation as before, until the distilled product 
has been increased to 15 fluid ounces. Finally, mix this with the remaining 
two pints of spirit. 
In this process, when the heat has been applied, and the temperature of 
the liquid has reached about 150°, numerous minute bubbles of gas are ob¬ 
served to issue from the surface of the copper, and these increase until the 
temperature has reached 170°, when nitrous ether begins to be formed, 
and the liquid, at the same time, becomes coloured with a salt of copper. The 
temperature now quickly rises to 175°, at which, if the heat applied to the 
retort be properly adjusted, it will remain with scarcely any variation 
throughout the process. At the temperature of 175° the distillation proceeds 
rapidly and steadily, the surface of the liquid in the retort being covered with 
a froth of about half an inch in thickness, and the space above it being filled 
with a transparent vapour of a yellowish colour. This colour is not due to 
the presence of nitrous fumes, but appears to be that of the ethereal vapour. 
The effervescence in the liquid is evidently not that of ebullition, but of 
chemical action, and this does not alter either in its nature or intensity, the 
distilled product continuing unchanged from first to last. I have never 
found it necessary to alter the source of heat while the distillation is proceeding 
