May 11, 1872.] 
THE PHARMACEUTICAL JOURNAL AND TRANSACTIONS. 
903 
any period of the operation, could be diluted with 
water to any desirable volume without decomposi¬ 
tion. This principle was now applied to oil of tur¬ 
pentine, assumed to be the most refractory in the 
category of oils. 
Two fluid drachms of officinal mucilage of acacia 
was placed into a broad, conveniently-sized mortar, 
and diluted with one fluid drachm of water. Half a 
fluid drachm of oil of turpentine was then added, 
and the whole triturated a few moments until the 
oil was emulsified. One and half drachms of oil 
was then added, in half-drachm portions, emulsify¬ 
ing each before adding the next: tliis was followed 
by one drachm of water. Five fluid drachms of oil 
was now introduced in the same manner as before, 
and again followed by half a drachm of water. 
After this three drachms of oil were again incorpo¬ 
rated as above, and still the emulsion retained its 
perfect appearance, and ever ready to extinguish 
quantities of oil to an almost unlimited extent. 
However, this was not required, and therefore the 
incorporation of oil was here discontinued, and the 
emulsion diluted with water. 
Upon these deductions, the following tlieorj' is 
established :—A concentrated, x>erfect emulsion is in 
itself the most rapid and efficient emulsifier, and 
possesses the property of emulsifying oil to an al¬ 
most unlimited extent. 
This theory is expressed in the following rule of 
the emulsion:— 
Introduce the emulsifier into a broad, conve¬ 
niently-sized mortar; this may be already a perfect 
emulsion, as the yolk of eggs, but if it is gum this 
must be in the form of mucilage, either thick or 
thin, according to the nature of the oil. Now pour in 
a small quantity of oil, and triturate this with the 
mucilage until a perfect emulsion has formed, then 
add the rest of the oil in small portions at a time, and 
not until the previous addition has been perfectly 
emulsified, adding small quantities of water at inter¬ 
vals, as the indications may require. Finally, when 
all the oil has been incorporated, gradually add the 
prescribed volume of diluent. When both a fixed 
and volatile oil are prescribed in an emulsion, the 
fixed oil must be emulsified first before the addition 
of the other .—The Pharmacist . 
Cjrajtttrs for Sttfotnfo. 
CHEMICAL NOTES TO THE PHARMACOPOEIA. 
BY WILLIAM A. TILDEN, D.SC. LOND. 
DEMONSTRATOR OF PRACTICAL CHEMISTRY TO THE 
PHARMACEUTICAL SOCIETY. 
Sodii Chloridum, Na Cl.—Chloride of sodium is 
found in greater or less quantity in the waters of all 
springs and rivers, and abundantly in sea-water. 
In the massive crystalline form, as “ rock salt,” it 
also occurs in beds of vast extent and considerable 
thickness, which are generally supposed to have 
been formed by the gradual drying up of inland 
seas. 
It is from this source that all the table salt of 
commerce is obtained. Bay salt is produced from 
sea-water. Common salt is the chief source of other 
sodium compounds. 
[§ It imparts a yellow colour to flame. The solu¬ 
tion is not precipitated by perchloride of platinum, 
but gives with nitrate of silver a white precipitate' 
(AgC’l) soluble in ammonia, but insoluble in nitric 
acid.] 
Common salt never consists of perfectly pure 
chloride of sodium, but contains small quantities of 
chloride of magnesium and of sulphate of sodium. 
The presence of the former explains the slightly de¬ 
liquescent character of ordinary salt, and its action 
in discolouring silver spoons left in contact with it. 
Spiritus jEtheris Nitrosi. —A solution of etliylic 
nitrite with aldehyd, and frequently other substances, 
in rectified spirit. 
When a mixture of alcohol and nitric acid is 
submitted to distillation, no nitrate of ethyl is ob¬ 
tained as might, at first sight, be expected; but 
when the acid becomes sufficiently concentrated, 
a reaction sets in, in which part of the alcohol is 
oxidized and part converted into nitrite of ethyl. 
C 2 H 5 HO + HN0 2 0 + C 2 H 6 0 = 
Alcohol Nitric acid Alcohol. 
c 2 h 5 no 2 -f h 2 o + c 2 h 4 o + h 2 o. 
Ethyl Nitrite Water Aldehyd Wuter. 
The aldehyd, which is the principal product of 
the oxidation of the alcohol, distils over with the 
ether, accompanied by traces of acetic acid, and 
often of other bodies. 
The process of the B. P. was devised with the 
view of obtaining a more uniform product by mode¬ 
rating and regulating the action of the nitric acid. 
Pharmaceutically speaking it is an admirable pro¬ 
cess, though it does not yield nitrous ether in a state 
even approaching purity. 
A solution of nitric and sulphuric acids in recti¬ 
fied spirit is distilled from a retort containing 
copper turnings. At a temperature of about 175°- 
178° F. the liquid becomes covered by a head of 
froth, and the liquid distils rapidly for some time 
till, at a certain point, the froth somewhat suddenly 
subsides; more nitric acid is then added and the 
process resumed. 
The copper was originally employed with the 
idea that it would, with the aid of the sulphuric 
acid, reduce the nitric to nitrous acid,— 
HN0 2 0 + H 2 S0 4 4- Cu = 
Nitric Acid Sulphuric Acid. 
HNOo + H 2 0 -f- CuS0 4 
Nitrous Acid Water Sulphate of Copper.' 
and that the latter would react in a simple manner 
upon the alcohol. Thus 
HN0 2 + C 2 H 5 HO = 
Nitrous Acid Alcohol. 
c 2 h 5 no, + h 2 o 
Nitrite of Ethyl Water. 
Or Nitrous Ether. 
This occurs, however, only to a limited extent, 
and consequently the resulting spirit still contains 
nearly as much aldehyd as the old-fashioned spirit 
of nitre. 
The aldehyd may be recognized by warming the 
spirit with an equal volume of liquor potass®. A 
peculiar yellow soapy-smelling, resinoid compound, 
characteristic of aldehyd, is deposited on cooling. 
It cannot, however, be made to reduce silver in 
the form of a mirror, as is the case with aqueous 
solutions. 
When any solution of nitrous ether is heated m 
a sealed tube with strong ammonia, nitrogen gas is 
evolved and alcohol generated. 
c 2 h 5 no 2 + nh 3 = 
Nitrite of Ethyl Ammouia 
C 2 H 5 HO + N 2 + H. 2 0 
Alcohol Nitrogen Water. 
