Page:The Journal of Tropical Medicine, volume 6.djvu/226

THE JOURNAL OF TROPICAL MEDICINE. (June 15, 1903.

194 rivers there. In the mechanical filter an artificial film of an intercepting nature is obtained by the addition of some substance which will form a fine deposit on the surface of the sand. Sulphate of alumina in the proportion of a half to two grains per gallon of water is most commonly employed. The coagulant, which forms a fine gelatinous precipitate on the surface of the filter, removes the colour as well as the suspended matter of the water, and as much as 98 to 99 per cent. of the bacteria. These filters are in covered reservoirs, and are placed under pressure usually by the admission of compressed air, and are cleaned by a reversed action of the filter, with sometimes the admission of steam. Their rate of filtration is generally about fifty times greater than that of the ordinary gravity filter.

Filtration on a small scale for domestic purposes is now usually effected by two kinds of filters—-the Pasteur- Chamberland and the Berkefeld: A few years ago there were on the market many kinds of filters, constructed of every variety of material; charcoal, asbestos, mag- netic carbide, spongy iron, polarite, and silicated carbon were among the number. They have, however, gone out of fashion, having been found wanting in their action on bacteria. They do not sterilise the water or render it free from bacteria. It is because the Pasteur and Berkefeld. possess this property that they have practically supplanted the others.

The Pasteur filtration is a purely empirical result, the uniform sterilising efficiency of the tubes being due to certain details of composition and manipulation in manufacture. It appears to depend on a_suriace attraction which the material exercises on protoplasm of microscopic dimensions. Air passed through the dry tubes emerges sterilised, and organisms smaller than the pores of the filter are arrested. Purification does not at first depend on the formation of a layer of slime as in sand filtration, for sterilisation begins immediately the tube is used, and occurs whatever may be the pressure of water. When steeped in water a Pasteur tube will not allow the passage of compressed air, and this circumstance enables a diagnostic test to be made of its bacterial soundness ; or when a number of tubes communicate with a single receiver of the soundness of the whole filtering system, which for this purpose is immersed in water, so that a stream of bubbles will issue from a faulty point when compressed air is forced into the filtered water chamber.

The disadvantages, of the filter are that is is not a gravitation filter but a pressure filter, requiring so much head of pressure before any considerable quantities can be obtained ; and that in consequence of the ordinary river water of the Tropics being muddy or slimy, the filter becomes practically useless, for it rapidly gets a coating on its outside, which completely blocks up the filter and puts a stop to any water passing through, even under pressure. The same objections apply to the Berkefeld filter, with the additional one that it is more brittle than the Pasteur, and is not adapted for either rough transport or frequent cleansing.

The pressure difficulty is, as a rule, easily got over, for there are few places where a little ingenuity will not supply a sufficiency of pressure; and if not desir- able to depend on this, there are numerous portable

exhaust types in the market which can be adapted to every circumstance.

The readiness with which the filter—the Pasteur- Chamberland and Berkefeld—is blocked up is a much more serious affair, and leads sooner or later to the abandonment of its use. None of these kinds of filters will be of general utility in the Tropics unless, as part and parcel of their structure, there is a rough filter attached, which shall first clarify the water and remove the slime.

The Berkefeld filter is on the same principle as the Pasteur-Chamberland. It consists of diatomaceous earth, made into a thick instead of a thin cylinder, and allows of water being filtered more rapidly. The same remarks as to disadvantages of the Pasteur-Cham- berland apply as much to the Berkefeld. a Hezmoglobinuria.

EMOGLOBINURIA DEI Matarica (The Hemoglobin- uria of Malaria), by Dr. De Blasi. Gazetta degli ospedali e. delle cliniche, 1903, No. 53.—The author states that hemoglobinuria may occur either during the attack of malaria or as soon as the afebrile period sets in. He is of opinion that hemoglobinuria is the result of the use of quinjne. Leprosy. A SuccessFuL ATTEMPT TO CULTIVATE THE “ BacIL- Lus Lepr,” by Van Houten. Journ. of Path. and Bact., 1902, No. 8, p. 260.—The author of this article states that although numerous attempts have been made to cultivate the Bacillus lepre, he is dubious as to whether the results were positive enough to prove that they were actually successful. In regard to his

own researches, he is satisfied that he has succeeded in ' obtaining a pure culture of the bacillus. The methods adopted by this observer are somewhat different to those generally in vogue. He inoculates broth, pre- pared with fish and beef and rendered slightly alkaline, with leprous material. From this broth he is able to obtain subcultures in a similar mixture, and, after several cultivations, subcultures can be obtained in beef broth. The pure cultures exhibit the morphological characteris- tics of the Bacillus leprae. The chief evidence, however, in the success of his efforts is afforded by the action of the leprous serum upon cultures of the organism. These bacilli, when mixed with diluted human serum, show the Pfeiffer-Bordet reaction. This reaction, which destroys

the bacilli, occurs both with ordinary serum and with ; leprous serum, but the reaction is much more marked ; with leper serum than with the ordinary human serum. — On the basis of this observation, Van Houten comes to — the conclusion that his organism is the specific agent

of leprosy.

Das Lepra Asyt Matunea IN Bompay (The Leper Asylum Matunga in Bombay), by M. Oppenheim. Wiener klin. Wochenschr., 1903, No. 21.—This interest-_ ing report furnishes an account of the arrangements and systems of the asylum, and specifies the various forms — of leprosy met with in India,