The other apparatus—Ronsard’s—is about similar in construction, but the power exerted in forcing out the liquid is not gas, as in the former apparatus, but compressed air, forced into the body of the reservoir by means of a pump.
The body of the apparatus consists of a cylinder holding about five gallons; this constitutes the reservoir containing the liquid to be injected. Outside of this cylinder and running alongside of it is the body of the pump. The pipe communicating the air forced inside the cylinder above the liquid enters the bottom of the reservoir, and, passing through the liquid, runs along the inner side of the vessel until it has reached a point almost to the top of the cylinder. In the center of the apex at the top of the cylinder is a small funnel connected to a pipe running inside of the apparatus; this pipe, which is furnished with a cock, is intended to conduct inside the apparatus the liquid poured in at the funnel; it will act also as a relief cock, should it be found necessary to relieve the pressure on the liquid.
This apparatus is not provided, like the other, with a pressure gage, from the fact that the pressure being the result of a mechanical cause, the operator will soon be able to judge the amount of pressure by the number of strokes of the piston.
The delivery pipe is similar in every respect to the one in the apparatus described formerly; the graduated tube outside showing the quantity of liquid inside the apparatus is also the same; in fact, the similarity between the two is striking. But the principal feature of the apparatus, and that which recommends it to the profession, is the perfect isolation of all the working parts of the apparatus from direct contact with the liquid injected. The greatest objection in this case, as in the other, is removed, as the most important part of the work, namely: that of compressing the air, is performed without any danger to the generator.
Another apparatus—that of Waldon—combines the two systems in one, and can be operated with equal facility either by means of compressed air or by means of gaseous expansion.
Still, these instruments require a certain amount of familiarity in the handling before they can be operated with efficiency, as, to a person not fully conversant with their mechanism, they may prove awkward.
The instruments of Messrs. G. Tiemann & Co., of New York, which I have employed so far very successfully, could be rendered perfect by adopting some modifications in their make.
GASEOUS COMPOUNDS.
Too little attention has been paid heretofore to the antiseptic powers of certain gases. It is a well known fact, that some of the gases which are the result of animal and vegetable decomposition are, to a certain extent, the means of their own disinfection; hence, some of these are endowed with deodorizing as well as antiseptic properties.