emptied into rubbish piles, upon gardens, or where there is a possibility of infecting poultry, or even into water closets.

(c) It is unsafe to sleep in the bed of a tuberculous patient, or to spend a great amount of time in the room of such a patient; least of all should young children be allowed to sleep in such a room.

(d) Individuals considered as predisposed to contract tuberculosis should be kept away from localities frequented by phthisical patients.

(e) One should not use objects contaminated by phthisis (linen, bedding, clothing, toilet articles, jewelry, hangings, furniture, playthings, etc.,) except after suitable disinfection.

(f) Rooms and houses occupied at watering places and resorts should be furnished in such manner that disinfection may be easily carried out after the departure of each invalid. It is the best plan of all to furnish rooms without curtains, carpets or hangings, to whitewash the walls, and cover the floors with linoleum.-Am. Lancet.

Immunity and Immunization.

These subjects were tersely and well discussed by Buchner at the recent Budapest Congress (Munchener Med. Woch., September 11 and 18, 1894). Summarizing, he said that the natural capacity of resistance against infection (so-called "natural immunity") depends on essentially different conditions. and causes from the artificial or acquired immunity. They are accordingly wholly different, and must be considered and investigated separately, although they can both be operative at the same time in the same person. The natural capacity of resistance rests, on the one hand, upon the bactericidal potency of certain fluid constituents of the organism (the so-called alexins); on the other hand, on inherited insusceptibility of the tissues and cells of the body against particular bacterial poisons. This natural resistance cannot, as a rule, be imparted to other organisms by means of the blood. Leucocytes play an important part in the natural self-defense of the organism. Yet this is because they secrete certain soluble substances which produce the beneficial effects, and it is not through any phagocytic action, phagocytosis being only

a secondary phenomenon. Artificially induced, or "acquired," immunity depends on the presence of modified, apharmactic (entgifted), specific bacterial products-the so-called antitoxines, either in the blood or in other tissues of the body, or in both. The antitoxines, and with them the artificially-induced immunity, can be carried in and with the blood and the milk. The action of antitoxines does not consist in the direct destruction of specific bacterial poisons when the two are brought into contact. It should rather be considered as developing only within the organism through its own instrumentality, in that a lessening (on the part of the living tissues of the organism) of the specific susceptibility to the poison is produced. Thereby the individual is rendered insusceptible and capable of resistance against that particular poison.-N. Y. Med. Jour.

Hydrogen Dioxide-H2 O2

L. D. Kostenbine, A.M., M.D., Professor Chemistry, Urinology and Medical Jurisprudence, Louisville Medical College, and Professor Chemistry Louisville College Pharmacy, in Louisville Medical Monthly, says:

This remarkable liquid which contains the greatest percentage of oxygen of any compound known, was, for sometime, considered as a mere solution of oxygen in water, and consequently was called oxygenated water. It was afterward obtained free from water and found to be a definite chemical compound of hydrogen and oxygen, and differing from water in containing twice as much oxygen. In this state it is a heavy, oily liquid, readily decomposing at ordinary temperatures, but if heated, with explosive violence, being converted into ordinary water and oxygen gas. When poured into water it sinks, being nearly half again as heavy as that liquid, but is miscible in all proportions with it. It has a somewhat bitter, astringent taste, and is colorless, transparent and without odor. It contains 94 per cent. of oxygen gas by weight, and will yield 475 times its volume of that gas. It bleaches the skin, hair, ivory, and destroys organic coloring matter, pus, and all organisms with which it comes in contact by liberating oxygen gas in a nascent or active state. It is resolved into oxygen and water by certain metals, such as gold, platinum, silver and

mercury in a state of fine subdivision, although the metals themselves undergo no change whatever. If the oxides of these same metals are brought into contact with it, not only does the hydrogen dioxide lose oxygen and become water, but the oxides lose their oxygen and are reduced to the metallic state, thereby evolving an additional amount of oxygen.

Strange as it may appear, with all its energetic oxidizing action, it has no effect on phosphorus, a substance which is so readily oxidized by the air.

The preparations found in commerce are only solutions of this compound in water, and sold in different degrees of concentration or strength, rated by the number of volumes of oxygen gas they can be made to yield. A fifteen volume solution is one that will give off fifteen volumes of gas from one volume of the solution. A ten volume solution will yield ten pints of oxygen gas from one pint of the solution, and so on. These solutions, although more stable than mere concentrated preparations, nevertheless decompose and lose their nascent oxygen on which its powerful antiseptic powers depend, and consequently we find the commercial brands varying considerably from their reputed strengths. The solution I find containing the greatest percentage of available oxygen, is the preparation known as Marchand's, which, when perfectly fresh, is about a fifteen volume solution.

There are quite a number of different methods of preparing aqueous solutions of this interesting compound besides the original method of Thenard, the discoverer. Usually, however, barium dioxide in the hydrated state and purified from all foreign matter, is decomposed by such acids as will make an insoluble compound with it. The United States Pharmacopoeia has adopted this compound under the official title of Aquæ Hydrogenii Dioxidi, gives a process of preparing it and describes it as a slightly acid aqueous solution of hydrogen dioxide, containing, when freshly made, about 3 per cent. by weight of the pure anhydrous dioxide, corresponding to about 10 volumes of available oxygen. It is made by the action of phosphoric acid upon barium peroxide. It must be borne in mind that it is essential to employ a small amount of free acid to preserve these solutions, but if too large a quantity it would

be a source of irritation when applied to denuded surfaces and inflamed mucous membranes, and consequently, officially, a preparation requiring more than 0.5 c. c. of volumetric caustic potash solution to neutralize .50 c. c. of it, does not come up to the U. S. P. standard.

Of the various brands of commercial dioxides I have examined, I find Marchand's to be the one which yields the largest amount of available oxygen under all conditions of exposure, and the one which contains the minimum percentage of free acid. All the marketable articles I have seen are free from barium compounds, but the majority do not come up to the 15 volume standard, but are 6, 8, 10 and 12 volume solutions. In addition to its medical uses, hydrogen dioxide can be employed to detect blood, in conjunction with freshly prepared tincture of guaiac. Although tincture of guaiac turns blue with a variety of substances, blood is not one of them. So in testing for a stain-say on clothing-moisten the spot with water, and afterward apply a piece of white filter paper; the slightest straw-colored stain on the paper suffices. Now, add to the spot on the paper a few drops of the guaiac tincture-no coloration. Add a few drops of solution of peroxide, when instantly the spot turns a deep azure blue. Of course if the spot turns blue by the guaiac alone, it can not be due to blood, yet it is possible blood may be present with some other substance which has that property, and hence the employment of peroxide, in that case, would be a source of fallacy. If there is no blueing by guaiac and peroxide together, then absolutely no blood is present.

Hydrogen dioxide can be determined quantitatively by permanganate of potassium solution acidified by sulphuric acid, and the quantity of oxygen gas evolved measured in an instrument called a nitro-meter, and calculated for normal pressure and temperature. One-half the oxygen evolved comes from the dioxide and the other half from the permanganate solution.

Another method, and the one commonly employed, is to add a volumetric solution of permanganate of potassium from a burette to a measured portion of a hydrogen dioxide solution, diluted with water and acidulated with sulphuric acid, until

the permanganate solution is rendered colorless, and then a few drops more of that reagent employed till a permanent faint pink coloration is given to the dioxide solution to indicate the completion of process. A slight calculation will give the strength of solution. There are other methods, but the two indicated are the best.

A solution of peroxide of hydrogen is usually tested by pouring a drachm of it in a clean test tube, together with an equal quantity of ether, then pouring into the tube a few drops of bichromate of potassium solution, and shaking the tube, when the etheral layer will become of a beautiful azure blue color, due to the formation of perchromic acid which dissolves in the ether.

To a few drops of nitrate of silver solution, add aqua ammonia enough to precipitate oxide of silver, then add hydrogen peroxide, when finely divided metallic silver separates. A solution of tannic acid in oil of vitriol and diluted will yield a yellow color when added to solutions of the peroxide.

Boiling Abscess Cavities.

The Paris correspondent of the Lancet describes a method employed by Jeannel of Toulouse in the treatment of localized tuberculous lesions, such as abscesses, ulcers, osseous and joint troubles, with boiling water as a cauterizing and bactericidal agent. The method is applied as follows: After having freely opened the seat of mischief and slit up any sinuses that may exist, he excises if the lesion involves a joint. All the caseous detritus is then removed by curetting and thorough sponging of the parts, all bleeding being arrested. Then salt solution, maintained at the boiling point in a recipient (coffee pot), is allowed to fill the cavity through a thick rubber tube. The cavity is then afterward filled and emptied, until a sufficient degree of cauterization is effected. It will be seen that this modus operandi is only possible in the case of a funnel-shaped cavity whose sides can be raised and kept apart by tenacula and which is unprovided with counter-openings-a condition frequently met with in practice. A second and preferable procedure is also employed by M. Jeannel. This consists in first filling the foyer with cold or tepid salt solu