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Grave and acute sounds

mission of sound. For Mr. Martin and me, at the distance of 951 m. [1040 yds.], this time was about 5.58."

We also ascertained anew, that grave and acute sounds are transmitted with equal velocity, which is agreeable to have equal velocity. theory, and has been several times observed. Tunes on the Playing on the flute, played at one extremity of the pipe, were transmitted Aute. to the other without any alteration in the intervals of the different intonations. It appeared to me only, that the very high notes were not heard so well as the low notes; and sometimes, when they were extreinely high, I lost them entirely; though I heard others that were lower, which, from the nature of the tune, I knew to be weaker than the former*.

Echo of the voice returned percatedly to the speaker,

but the sound at the other end single Detonations.

I also observed, that, in speaking through the pipe, I heard my own voice repeated by several echoes, which suċceeded each other at exactly equal intervals. In our last experiment I counted no less than six, about 0.5" dis tant fron. each other. The last returned after a little less than 8"; that is, in the time requisite for the transmission of the sound to the other end of the pipe. These pheno inena occurred equally at each extremity of the pipe, when we spoke into it. Of this I satisfied myself by requesting Mr. Martin, through the pipe, to observe them, without communicating to him my results: and his, which he re ported to me immediately in the same way, were perfectly similar. The number of echoes and their intervals were the same, and the total of the time was the same also; but the person who is spoken to never hears but one sound.

Lastly, detonations capable of producing a considerable agitation in the air were transmitted to the other end of the A pistol fired pipe with an intensity proportional to their strength. Reports of a pistol fired at one end occasioned a considerable candle at the explosion at the other. The air was driven out of the pipe

at one end

blew out a

other.

Since this paper was read, I have found, that the person who played the flute, having very weak lungs, could with difficulty bring out the high notes, and was frequently obliged to skip them entirely. It was very natural therefore, that I should not hear them: but I have thought proper to let my first account remain, that the reader may see I reported faithfully the smallest particulars; and that my veracity in this circumstance may confirm the other results 1 observed.

with sufficient force to give the hand a smart blow, to drive light substances out of it to the distance of half a yard, and to extinguish a candle, though it was 950 m. [1039 yds.] distant from the place where the pistol was fired.

V.

Observations and Experiments on Pus. By GEORGE
PEARSON, M. D. F. R. S.

THE

(Concluded from p. 27.)

SECTION VII. Conclusions.

HE statement of the properties of pus in the foregoing General inquiry I hope will be found to be true; and I submit to the conclusions. judgment of others whether or no the following inferences

are legitimately established.

three distinct

pro- substances.

1. That this fluid essentially consists of three distinct sub- Pus consists of stances, viz. 1. An animal oxide, which, among other perties, is distinguished by its being white, opaque, smooth, of the form of fine curdy particles in water; not dissoluble in less than 1000 cold waters; not coagulable into one mass like serum of blood by caloric, alcohol, &c.; only rendered more curdy by water from 160° to 170°; but readily diffusible. -2. A limpid fluid resembling serum of blood in its impregnations, and in its coagulability by caloric, alcohol, &c.; in which the opaque oxide is diffusible but not dissoluble, and which is specifically lighter than that oxide.-3. Innumerable spherical particles visible only by the microscope in this opaque oxide, and in small number in the limpid fluid; not coagulable by any temperature to which hitherto exposed, and not destructible by many things which combine or destroy the opaque oxide; and these globules are specifically heavier than water*..

My obligingly attentive pupils, Mr. BURTON, and Mr. STANSFELD, house-surgeons of the Lock hospital, collected for me a sufficient quantity of gonorrheal matter to determine, that it consisted of the three ingredients here stated.

VOL. XXX.-Ocr. 1811.

I

2. That

Visible curdy

masses,

Red or dark

2. That the visible curdy masses, as well as the fibrous or leafy parts, almost always contained in smaller or larger quantities in pus, may be considered as self-coagulated lymph, which in its fluid state is secreted without having the state of aggregation produced in it like that of the essential opaque oxide of pus.-Sect. VII, 1.

3. That the reddish, the blackish, and the dark brown colour of pus. colour of pus depends upon the red part of the blood effused or secreted from the same vessels, or from contiguous ones which secrete pus.

Irregular

masses.

Fætor.

Adventitious contagious matters.

Secretion of

4. That on some occasions the clotty and irregularly figured masses found in the pus may depend upon disorganization or breach of the contiguous solid parts.

5. That whenever pus is fœtid to the smell, a portion of it is in the state of putrefactive fermentation, which may be removed by ablutions with water.

6. That there are certain adventitious matters liable to be contained in pus not hitherto rendered palpable to the senses, but known by their effects in exciting contagious diseases; such as small-pox, syphilis, &c. These matters are produced by a specific action in the secretory organs of pus, by such matters themselves either contained in the circulating blood, or on the secreting surface.

7. That the essential substances of which pus consists, as pus from the well as some of the adventitious ones (Sect. VII, 1, 2, 3,

blood.

Sources of the differences of

pus.

6),

are separated from the blood by a peculiar organization belonging, or attached to the blood-vessels: which organs of separation or secretion are not only excited to the action which produces pus in deseased states, but they are evidently influenced by the states of other distant organs of the animal œconomy; hence many varieties in the properties of the purulent matter.

8. That the varieties of purulent matter relate to differences of quantity-the proportion of the essential substances (1)-and the adventitious parts (2, 3, 4, 5, 6,). The creamlike pus consisting of almost purely the opaque oxide and limpid liquid (I, 1, 2,). The curdy containing a large proportion of coagulated lymph, or broken down solids. The serous abounding in limpid fluid. The riscid depending

upon

upon the coagulation, and perhaps, inspissation, by union of neutral salts with the opaque oxide.

tion.

9. That as the essential parts are secreted in a limpid state, Self-coagu but presently become opaque, owing to a large proportion the blood and lated lymph of spontaneously coagulating, and thus becoming the opaque serum separaoxide, mixed with the serous liquid, and innumerable spherited by secre cal particles (Sect. VII, I, 1, 2, 3), it seems reasonable to infer, that these matters are the self-coagulated lymph of the blood and serum, separated by the secretory organs; which act of secretion determines the subsequent state of aggregation of pus, and the globules are at the same time formed analogously to their formation by other secretory organs. How far they are those of the blood altered by secretion may be determined hereafter. It is a collateral proof of this inference, that very thick pus affords from one sixth to one seventh of exsiccated brittle residue, which, as I have found, is nearly the same proportion afforded on the exsiccation of the buffy coat of inflamed blood; while very thin pus affords on exsiccation from one eighth to one eleventh of brittle residue, which is the proportion to be expected from a mixture of serum of blood and self-coagulated lymph, as I have ascertained.

earthy ingredients.

10. That the constant inpregnating saline and earthy Saline and ingredients of pus are dissolved in the serous fluid; and are all separable along with the serum, by ablutions with water, from the opaque oxide (1), except a portion of the phosphate of lime. These impregnations are the same as those of serum of blood, and of expectorated mucous matter, viz. muriate of soda; potash neutralized by animal matter or a destructaible acid; phosphate of lime; ammonia neutralized probably by phosphoric acid; with a sulphate, and traces of some other matters mentioned in my former paper. The proportion of these impregnating substances is as the proportion of limpid or serous coagulable fluid, and of course inversely as the proportion of the opaque oxide of pus; but it varies in different cases in given proportions of this oxide, and the limpid fluid. In general, if not always, a given quantity of pus contains a smaller proportion of saline matters than an equal given quantity of expectorated mucous matter, but a given quantity of the limpid coagulated fluid

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Calculi in abscesses.

Different se. cretions from

the same

rent states.

contains a greater proportion of saline matters than an equal given quantity of serum of blood. Hence the thicker the pus the less irritation to the sore which secretes it, and commonly the less the inflammatory or other action of the secreting surface. In different cases, however, the proportion of impregnating saline substances to one another is liable to vary, especially that of phosphate of lime; hence, though rarely, calculi occur of this substance in the cavity of the abscess*. Hence too the exsiccated pus is liable to become soft and moist, from the proportion of neutralized potash being greater than usual; and even deliquescence sometimes occurs of the exsiccated limpid fluid.

12. That the same organs, according to their different states, secrete from the blood merely water impregnated organs in diffe. with the saline substances of the serum of blood; also this fluid containing various proportions of coagulable matter like that of serum of blood; and serous fluid with self-coagulable lymph, which affords curdy masses: likewise this serous fluid, together with this matter which coagulates of itself after secretion, highly impregnated with invisibly small particles, in such a state of aggregation, as to constitute the thick opaque fluid called pus--which states of the secretory organs are generally attended with inflammatory action, but frequently also without any symptoms of such action.

Consistence of pus.

Distinction of

13. That beside the consistence of pus depending upon the proportion of serous limpid liquid, and opaque matter, it also probably depends upon the mode and state of coagulation of the matter which affords this opaque part; analogously to the different states of consistence of the coagulated blood itself, according to the different conditions of the animal

œconomy.

According to the above inferences, I trust, a distinct and pus from other definite notion of the substance to be considered as pus is

matters.

Stones in the lungs.

* On examining the lungs of a patient who died of pulmonary consumption, concretions were found in a large vomica from the size of mustard seed to a pepper corn, which Dr. E. N. BANCROFT reserved for my inquiry. I found they consisted chiefly of phosphate of lime, with an unusually small proportion of animal matter. In another patient of Dr. NEVINSON, matter was coughed up, consisting chiefly of phosphate of lime and animal matter, nearly one of the former to three of the latter.

exhibited

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