A true disinfectant should be at once a deodoriser (destroyer of odours) and an antiseptic (destroyer of low forms of life). The presence of sewage gas in an apartment may be detected in the following way: - Saturate unglazed paper with a solution of 1 oz. pure lead acetate in 1/2 pint rain-water; let it partially dry, then expose in the room suspected of containing sewer gas. The presence of the latter in any considerable quantity soon blackens the test-paper.

The Imperial Board of Health of Berlin have recently published the experiments made by Dr. Koch, with a view to establishing the true value of a number of reputed disinfectants, of which the following is a brief summary: -

1. Most surgeons have been satisfied to wash their hands and clean instruments with a 2 per cent, solution of carbolic acid: such a solution is almost inert, and a 5 per cent, solution is necessary for the purpose. Carbolic acid dissolved in oil or alcohol proves to be totally inert, and has not the slightest effect on the vitality of micrococci or bacilli.

2. Sulphurous acid was found to be powerless against spores; bacilli and micrococci, when exposed to the fumes in a box, were killed within 20 minutes, but were very little influenced, or not at all, when exposed to the fumes in a room at the usual temperature.

3. Chloride of zinc showed itself just as harmless. A 5 per cent, solution exerted absolutely no influence on the spores of anthrax, notwithstanding the same had been exposed to the action of the remedy for a period of 30 days.

4. The spores of the bacilli were killed by chlorine water fresh prepared, 2 per cent, bromine water, 1 per cent, aqueous solution of corrosive sublimate, 5 per cent, solution of permanganate of potassium, 1 per cent, osmic acid, within 1 day; formic acid, 4 days; oil of turpentine, 5 days; solution of chloride of iron, 4 days; 1 per .cent, arsenious acid, 1 per cent, quinine (water with muriatic acid), 2 per cent, muriatic acid, within 10 days; ether, within 30 days.

5. Inert or possessing very little influence: distilled water, alcohol, glycerine, oil, carbon bisulphide, choloroform, benzol, petroleum-ether, ammonia, concentrated solution of common salt, bromide and iodide of potassium, 1 per cent, sulphuric acid, sulphate of zinc and copper, alum, 1 per cent, permanganate of potash, chromic acid, the chromates and bichromates, chlorate of potash (5 per cent.), boracic acid (5 per cent.), acetic acid (5 per cent.), tannic acid (5 per cent.), benzoate of sodium (5 per cent.), quinine (2 per cent, in water 40, alcohol 60), iodine (1 per cent, in alcohol), thymol (5 per cent, in alcohol), salicylic acid (1 per cent, in alcohol, 2 per cent, in oil).

6. As regards remedies which prevent the further development of spores the following results were obtained. The first number means retarding the development, the rest totally preventing it: -

Corrosive sublimate

1 : 1,600,000

1 : 320,000

Oil of mustard ..

1 : 330,000

1 : 33,000

Arsenite of potash

1 : 100,000

1 :10,000

Thymol.. ..

1 : 80,000

Oil of turpentine ..

1 : 75,000

Hydrocyanic acid

1 : 40,000

1:8,000

Oil of peppermint

1 : 33,000

Chromic acid ..

1 : 10,000

1:5,000

Picric acid ..

1 : 10,000

1:5,000

Iodine.........

1 : 5,000

Salicylic acid

1 : 3,300

1:1,500

Permang of potash

1 : 3,000

Muriatic acid ..

1 : 2,500

1:1,700

Camphor •. ..

1 : 2,500

Eucalyptol .. ..

1 : 2,500

Benzoic acid.. ..

1 : 2,000

Borax ......

1 : 2,000

1:700

Carbolic add.. ..

1:1,250

1:300

But as, for purposes of disinfection, the micro-organism must be killed, and in the shortest possible period, and the effect of retarding the development of the spores (antiseptic) is not sufficient, only the following remedies can, according to Koch's experiments, be said to be of value: corrosive sublimate, chlorine, bromine, iodine. Bromine in form of vapour is, as concerns rapidity of action, superior to chlorine and iodine. (Medical and Surgical Reporter.)

In a pamphlet recently published by Dr. John Dougall, of Glasgow,* containing an account of a series of experiments upon putrefiers and antiseptics, are some important facts which bear upon the real value of certain disinfectants held in esteem by the public. Dr. Dougall's experiments were made to ascertain (1) whether putrefaction can be accelerated by adding certain chemicals to fresh organic fluids; (2) the relative antiseptic powers of different bodies, as evinced by their preventing the appearance of fungi and animalcules in organic fluids with which they are mixed; and (3) the relative aerial antiseptic powers of different volatile bodies, as evinced by their preventing the appearance of fungi and animalcule in organic fluids exposed to their vapoury and by their action on vaccine lymph. Solutions of soda, potash, ammonia, and their salts, were added to solutions of beef-juice and hay infusion, as were also solutions of pepsine, lime, spirits of nitric ether, acetone, acetate of morphia, sugar, sulphate of magnesium, charcoal. Simple solutions of beef-juice were experimented upon at the same time.

The results obtained show that the alkalies and alkaline earths, and their alkaline and neutral salts, with a very few exceptions, hasten decomposition when present in small proportion in fluids containing organic matter. Hence it follows that all domestic soap-suds, spent lye from soap, bleach, and alkali works, and all liquors more or less alkaline, will hasten the putrefaction of organic matters in sewage; all the chemical solutions experimented with appear to hasten putrefaction, except ammonia, permanganate of potash, and biborate of sodium, but these do not seem to retard it. Soda, potash, nitrate and chlorate of potassium, and lime, appearing specially vigorous as putretiers at the outset of the experiment, Dr. Dougall infers that they will continue so throughout. It will be observed that salt, saltpetre, and sugar, substances which preserve meat when used in large quantities, act as putrefiers when added in small quantities to solutions containing organic matter.

On Putrefiers and Antiseptics.' By John outfall, M.D., Medical Officer of Health for the Burgh of Kinning Park, Glasgow.

In the experiments made to ascertain the antiseptic powers of different substances, solutions of which were mixed with solutions of beef-juice, egg-albumen, and of these mingled with urine, mercuric chloride, argentric nitrate, and benzoic acid (1 in 500) alone prevented the appearance of animalcules or fungi in the solution of beef-juice, no change being found in 182 days; they exercised the same influence on the solution of egg-albumen, as did also in addition chromic acid, cupric sulphate, and potassic dichromate, for a like period of 182 days. Chromic acid, cupric sulphate, mercuric chloride, and benzoic acid alone prevented the appearance of both animalculse and fungi in the mixture of beef-juice, egg-albumen, and urine. On the other hand, animalculse and fungi appeared in the different solutions, when treated with chloride of zinc, in 4 to 18 days; with carbolic acid, in 12 to 50 days; with sulphate of iron, in 4 to 40 days; with sulphurous acid, in 4 to 24 days;. with chloride of lime, in 24 to 40 days; with chloral um, in 2 to 11 days; the time seeming to vary in an irregular manner with the different substances when applied to different solutions.