422 APPARATUS FOR MAKING DILUTED NITRO-HYDROCHLORTC ACID. 
which will probably meet every requirement, ensuring the product always 
being of the same strength. The acid of the British Pharmacopoeia is variable, 
principally because the result depends much upon the surrounding atmo¬ 
spheric influences, temperature, etc., as well as upon the size of the bottle in 
which the acid is kept before diluting. My apparatus is very simple in form, 
and easily managed. It consists of a large bottle (A) with a wide mouth, 
into w hich is ground a smaller bottle (B). This lat¬ 
ter has two holes (b b) drilled in it near the shoulder, 
corresponding to two grooves in the neck of the large 
bottle (A), which grooves are so ground as to allow 
the gases generated in B to pass into A, but not to 
escape into the air. By turning the inner bottle half 
round the connection is cut off. C is a clamp to se¬ 
cure the stoppers. In the outer bottle A is placed 
the water with which the acid is to be diluted ; in the 
inner bottle the mixed acid. The bottle B is then 
placed in A in such a manner that the holes b b and 
the grooves correspond, and by means of the clamp 
C the whole is made secure. The strong acid and the 
water remain thus separated twenty-four hours, ihe 
chlorine, chloronitrous, and other gases pass through 
bb into A and become absorbed in the water. During 
the time the acid is ordered to be kept before diluting, 
it is advisable to shake the apparatus a little to fa¬ 
cilitate the liberation of the gases in B, and the ab- 
The dilution of the acid is effected by simply placing 
the"apparatus on its side, so that the openings b b are vertical, when the acid 
will run from B into A. When part of the acid has thus run out, dilute it 
by shaking the bottle, then remove the clamp C and carefully loosen the 
stopper in B, so as to ascertain if there is pressure within. If there should 
be pressure replace the clamp, and continue the dilution until, on loosening 
the stopper, the pressure is found to have diminished below that of the atmo¬ 
sphere, or in other words, there is suction from without inwards. The stopper 
in B should then be removed so as to equalize the pressure within and without 
the apparatus. If this precaution be neglected, the stopper will be drawn in 
so tightly that it will be difficult to loosen without breaking the bottle. This 
great diminution of pressure may be attributed to some oxygen of the air, 
originally contained in the apparatus, entering into combination with the other 
gases, and forming with them soluble compounds, and to the decrease in 
volume that invariably accompanies the dilution of acids. Having finished 
the operation, pour the contents of B into A, and the latter being fitted with 
a stopper, may be used as the stock bottle. 
The same process may be conducted in a tube and a wide-mouthed bottle; 
a more simple arrangement, but inconvenient, because of the difficulty of 
getting the tube in or out without breaking either it or the bottle. I have 
broken three bottles in attempting to substitute a tube for the inner bottle. 
In two instances the breakage was caused by the tube falling obliquely from 
one side of the bottle to the other in the process of dilution, and in the third 
instance the bottle was broken by the tube dropping to the bottom during 
insertion. Various forms of apparatus will be on the table at the phar¬ 
maceutical meeting for January. 
The advantages of a bottle of this kind are evident. 
In the first place the product is always the same, which is most important 
to pharmacists. 
Secondly, the gas or gases to which this acid owes its peculiar properties 
are all contained in the product. 
