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Journal, June

III.-On an Apparatus for collecting Atmospheric Particles.

By R. L. MADDOX, M.D.

PLATE LIV.

To establish fully any relation between "dust and disease," whether these terms be used in their ordinary or scientific sense, needs an accumulation of evidence which is only likely to be gathered by a multiplicity of observations and experiments, demanding the patient and careful attention of numerous observers, and which, from the minute and varied character of the atmospheric particles, we may expect to long elude our strictest investigations.

Physicists by a beam of electric light may make known the reality of minute atoms floating in the ordinary air, and heat confirm the evidence that some at least are organic in their nature; but these two forces by no means prove those particles living germs; and even suppose they did this, they could not make us acquainted with the genus or species, or prove them carriers of contagion, or whether they were deadly in their nature, or simply germs of innocuous protophytes, at least so far as we know, as regards ourselves.

Nor is the question settled by the application of any mode of straining these particles by a cotton sieve. The utility of cotton in checking their passage has been noted by many observers, and was employed by Drs. Billings and Curtis of the U. S. army, in their experiments related in the valuable Report on the Cattle Plague in the United States, published by order of the Commissioner of Agriculture, 1869, Washington; they confirmed the singular property of bacteria, vibrios, and molecules, passing through moistened filtering paper, while yeast cells are checked, as pointed out previously by Mitzscherlich, and moreover they marked the imperviousness to all these bodies, by vegetable parchment, which permits the transit of fluids.

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Dr. Tyndall has shown us that organic matter may escape destruction to a great extent when air is drawn somewhat slowly over fragments of glass, wetted with concentrated sulphuric acid," also "over fragments of marble, wetted with a strong solution of caustic potash," or when "permitted to bubble through the liquid acid and through the solution of potash," and likewise when rapidly passed through a red-hot platinum tube, containing a roll of platinum gauze. Valuable as these observations are in themselves, we are but little nearer the chief question, which is left open as to the vitality of such organic particles, or their relation to disease.

Is there then any other plan than that which has been adopted by those who have taken pains to investigate for themselves, which may help forward the solution of this question, at least under one aspect? It is not sufficient to gather into water the floating germs

by any form of aspirator, or by shaking together frequently admitted volumes of air and distilled water; for this reason, that before you have proof of having entrapped any living molecules, admitting the purity of the water, you have to allow deposition, decant and examine the deposit by droplets under a high power, at least an eighth objective, and are even then, under the most careful scrutiny, by no means certain that very many of the lightest and minutest have not been either poured away or passed unnoticed.

A most delicate scum is sometimes seen on the water prior to decanting the mass; but this, so far as I am aware, has been entirely overlooked, and only the deposit examined; yet such scum has afforded different objects to those in the sediment. I am not in any way alluding to artificial infusions of vegetable, animal, or mineral matter in water; in the two former, the scum is too evident to escape observation. Nor does it follow, if the minutest germs be living, that they should subside at all; they may move through various depths unrecognized. The plan I propose is to try and entrap these atmospheric motes into a small compass, and under ordinary conditions of the external air; then, without allowing more than a few hours to elapse, proceed to their examination; for this reason:-Suppose an apparatus, where the air is drawn for weeks over or through the same water, and let us further suppose numerous germs were obtained, and a due calculation made of even the quantity of air drawn through hourly, it by no means follows that all those germs were drawn direct from the atmosphere, for those which have their habitat in water or damp places may have germinated and divided many times ere the experiment is finished, such subdivision or repetition giving false conclusions; and, moreover, many may have perished under the conditions employed to detect them.

If, then, we can draw these particles into a small space, the next object would be to try and make them pass through at least some of their phases of life, under careful watching with the microscope. Even supposing we have entrapped and developed some of the germs, we shall not have established their relation to disease; to do this would require a very numerous and careful course of observations; but one thing we shall have done, and that is have determined, at least partially, most of the largest of these germs be not those of the commonest forms of mildew, and such as we meet with continually in our food, and which most probably have not the slightest relation to disease, and the minutest, those which are ranged among the monads, bacteria, and vibrios.

To assist in this inquiry I have made the following apparatus as a hollow wind vane, but which can be used in various ways, and by which I hope to obtain results bearing on this important question, which as yet cannot be admitted as settled.

On reference to Fig. 1 (Plate LIV.) it will be seen as in use as

Journal,

a vane; but by changing the position from horizontal to vertical, attaching another short tube (f, Fig. 4), with a metal pipe terminating in a small funnel, and placing a lighted lamp beneath it, it can be used over a cesspool in any nook or corner, in an ordinary room, in a cow-shed or stable, or near a patient suffering from any infectious disease.

It consists in the main of two light tin funnels (a, b) (one rather larger than the other, and supplied with four wing offsets), united by two or more stout brass tubes for convenience of use. The smaller funnel has a diameter of 5 inches by 3 inches in depth, the larger of 5 inches by 34 inches in depth. The smaller funnel is continued into a tube of 1 inch diameter by 6 inches long, to the end of which is fixed or screwed a conical finely-turned cone, with a pipe nozzle (Fig. 5) having a screw thread on its outside and a tapering bore within. On the sides of the 6-inch tube, at alternate positions, are placed three smaller funnels 1, 2, 3. The tube of the funnel fits tightly into the brass tube (c), which is 2 inches long by 13 diameter; the short tube of the large funnel fits over the brass tube (d), which has nearly the same measurements as (c), and thus the centre of gravity can be easily found.

The brass tube (e) has at its junction with (d) an internal thread screw, and is free throughout its length. The other tube (d) has its external thread screwing into (c), but moreover a finer internal thread into which is screwed the diaphragm stage plate (e, Fig. 2), and which consists of a thick milled plate of brass, with a fine thread outside, and pierced with a central hole about 7ths of an inch in diameter, and by a series of six small holes external to it (Fig. 3, e, e). On the side facing the nozzle of the 6-inch pipe of the smaller funnel a narrow ring or raised edge is left in the turning, and abutting nearly against its edge on either side are two bent wire springs. Between this narrow ring and the springs is inserted a clean thin covering glass, gths of an inch square (Fig. 2, e). On the surface of the cover facing the aperture of the nozzle, which can be separated from it a variable distance, is placed a minute quantity of any prepared medium of a transparent and glutinous nature, but somewhat hygrometric, as glycerine or purified treacle with acetate of potash, &c., or the fluid medium, modified if necessary, suggested in my article "Mucor Mucedo," in the January No. of this Journal for the present year; adopting the most useful, if the cover is to be placed on a growing slide (as suggested in the same paper), or in a cultivating apparatus, or to be simply examined without attempts to development.

From the under-surface of the stout brass tube (c) is fastened a smaller tube with a solid end, into which is drilled a small conical depression, to receive the pointed end of the support or pivot (k), the other end of the support having a screw and nut by which it is fastened to the surface-plate of a tripod stand.

The aperture of the large end of the funnel (b) may be partially closed if thought proper by a ventilating fly-wheel, supported centrally by a steel pin with sharp ends embraced between two straps of brass, fastened to the internal face of the funnel by a screw and nut at about one-third of its depth from the open end; its rotation may tend to increase the current when used with a lamp, otherwise it is, I find, unnecessary. To use the apparatus vertically, screw the extra brass tube (Fig. 4) on to (d), and slip over the end of the funnel as before; fix into the short tube on (f) the gas-pipe (g), with its small funnel attached (p), and support the whole by one of the retort-holders of the laboratory, or in any convenient way, and place beneath the open end of the little funnel a lighted oil lamp to generate a current above the nozzle; hence it must be placed at such a distance from the apparatus as not to influence materially the current through its proper course. It can be used with water as an aspirator if desired, but my object has been to avoid this. Its position above the surface of the ground may vary from a few to many inches, according to choice. I use it at present 4 to 5 feet above the ground, but think 3 feet may be preferable. If it be desired to test the efficacy of various vapours or fluids as disinfectants or destructive of life in the germs, an extra nozzle (Fig. 5, h) can be screwed on the ordinary one (i), and made as a flat box having a small nozzle projecting from the cover, looking towards the thin glass. If this narrow box, which should be platinized inside, be packed with fine cotton wool, damped at one part with any article, as creosote, tinct. of the muriate of iron, or solution of quinine, or a particle of hypochloride of lime placed at one part, the particles from the air may be supposed to be entrapped amongst the fibres; but the cotton-wool should, before use, be soaked in absolute alcohol for half an hour, and squeezed dry between heated plates of glass; or gun-cotton might be used if thought more free from error. The wool from opposite the nozzle might, in each case, be removed with a pair of fine scissors and forceps, placed in a deep growing slide with some medium, and set aside for observation. If only a cursory examination be intended of the glass covers, I find a square, half an inch across, drawn on the clean surface of an ordinary 3-inch × 1-inch slide, with a little roll of soft beeswax, makes a very good temporary cell. Care must be taken to apply only a minute quantity of the glutinous material to the centre of the thin cover. If two or three diaphragm stages (e) be made, one could be screwed into place when the exposed one is removed.

It is not pretended that this form is the only useful one or the most convenient that can be adopted, but as it has now been in use some days, I find it answer its chief purpose very well, and is exceedingly easy to manipulate. The advantages claimed are, ready

VOL. III.

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application at any spot, the collection of the atmospheric particles into a small space in such a manner as to be at once microscopically examined with a th or th objective, placed on a growing slide, or some form of cultivating apparatus for further observation, or mounted permanently. The difficulty is to select the best cultivating medium. Hitherto I have found besides (débris) organic and mineral matters, pollen grains, minute germs of various fungi or protophytes, and excessively minute bodies, "molecules," "globules," &c.; none were seen in motion. All seem to vary abundance with the force of the wind and dryness of the ground.

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This apparatus is deficient as regards crucial tests, but for general use it is efficient, and may, by continued employment, be of service. If any doubt exist as to the medium furnishing the spores, it can be treated as though it had been exposed; hence thus far we have fairness in the results.

I believe it will be only by constant, varied, and multiplied research, we shall ever obtain any answer to the important question of "dust and disease;" hence my excuse for trespassing on the pages of this Journal, in the hope others may be induced to give the apparatus a fair trial or suggest something more useful.

P.S.-The examination of the collections made over forty days has shown that in this immediate locality, at this period, the air cannot be considered as loaded with microscopic germs; the largest number visible and counted as such on one cover being twentyone (not including bacteroid bodies). A few only have germinated; they are under observation.

The photographs were difficult to execute to secure the appearance of the minutest granules, as many of the large particles of sand, &c., were much out of correct focus; still I preferred this method as more truthful than any hand drawing, especially for Nos. 2 and 3. Some of the particles, which, under the low power used to photograph them, appear in the prints as "globules "—with globules"—with clear centres and dark outlines-with higher powers were found very irregular in form. [The drawings in the Plate are selections from some of Dr. Maddox's photographs.-ED. M. M. J.]

IV.-The Magnesium and Electric Light as applied to Photomicrography. By Brevet Lieutenant-Colonel J. J. WOODWARD, U. S. Army.

THE following very interesting remarks constitute the report by Dr. Woodward to the Surgeon-General of the United States Army:

I have the honour to inform you that on the 25th of October

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