the ether in oxygen gas; for if it is well founded, the combustion in this gas should be attended with flame.

On calling to mind the different experiments in this memoir, we shall see that there is not one which authorizes us to consider iodine as a compound body, or as a substance containing oxygen. On the contrary, we must be struck with the resemblance which it bears in some cases to sulphur, and in others to chlorine. Like them, it forms two acids, one by combining with oxygen, the other by combining with hydrogen : and we may have remarked that the acids formed at once by the combination of chlorine, iodine, and sulphur, with the elements of water, present this remarkable property, that when the acid formed by oxygen has its elements very condensed, that formed by hydrogen has them very weakly united.

Thus sulphur takes oxygen from iodine, and iodine takes it from chlorine ; but, on the other hand, chlorine takes hydrogen from jodine, and iodine from sulphur.

If we follow this analogy still further, we find that it holds likewise with respect to carbour; for sulphur deprives it of hydrogen, bút yields to it oxygen. Thus it would appear that the more a body condenses oxygen, the less it condenses hydrogen.* This is, with

* out doubt, a cause why the very oxidable metals, as iron, manganese, &c. do not dissolve in hydrogen. I say one of the causes; for if it were the only one, we could not see how mercury, silver, and gold, do not combine with hydrogen, though they have a very weak affinity for oxygen.t.

The other analogies which iodine has with sulphur and chlorine are very numerous. Some iodates resemble the chlorates exactly; but most of them have a greater analogy with the sulphates. The iodurets, sulphurets, and chlorurets, in general exhibit the same phenomena with water; and the action of sulphur, iodine, and chlorine, upon the oxides, with or without water, is exactly similar

. In short, all the properties of iodine may be classed between those of sulpliur and chlorine. It is not necessary to remark, that though

Was W Its cha 200

I

its ! fine the and

was

MOV with was 492 and

B

I have restricted myself to compare iodine with sulphur and chlorine, we might find analogies, though less numerous indeed, between it and phosphorus, and several other bodies ; but I thought it better to compare it only with those bodies to which it bears the greatest resemblance, and among which I conceive it ought to be classed. I. have been led by this to show that sulphur possesses all the general properties of chlorine, and that we ought in consequence to place it among those bodies which form acids by combining with hydrogen.

(To be continued.)

ARTICLE II.

Analysis of the Excrements of the Boa Constrictor. By Dr. Prout

The substance sent me as the excrements of the boa constrictor was solid, of a white colour inclining to yellow. Fracture earthy, When rubbed on a hard surface it left a white mark like chalk. Its feel, however, was rather more dry and harsh than that of chalk, and it was more friable than that substance, Smell faint. and mawkish. Sp. gr. 1385.

I.-A. After making a few general experiments to ascertain its nature and composition, 50 grains, well dried and in a state of fine powder, were digested for 24 hours in dilute 'muriatic acid; the mixture being occasionally, during that time, gently beated and well shaken. On adding the muriatic acid no effervescence, was perceived. The acid was then poured off, and in order to remove the whole of it, the substance was repeatedly well washed with distilled water, which washings were added to the acid. It was now carefully dried and weighed, and was found to have lost 492 grs., which, of course, were taken up by the muriatic acid, and remained in solution in it.

B. On the substance which had been left: undissolved by the :: acid, and which had become of a -bluish tinge, a solution of pure : potash was poured, which, on the application of heat, completely dissolved it, forming a solution transparent and nearly colourless. To this solution, while still warm, was added muriatic acid in ex-.. cess, which occasioned a copious white precipitate in the state of very minute but distinct grains, which, after having been well washed, was collected and dried. The following were its' pro- . perties. It existed, as before stated, under the form of very :: minute grains of a beautiful bluish white pearly appearance. No smell. Nearly insipid. Very sparingly soluble in cold water ; but rather more soluble in warm, and its solution faintly reddened litmus. Insoluble in alcohol. It combined with all the alkalies, earths, &c., forming compounds very little soluble in water. When nitric acid was poured upon it and heat applied, it was en

50

tirely dissolved ; the solution, after some time, acquired a beautiful deep rose or crimson colour," which stained the skin and other animal matters of the same tinge. The colour, however, of the solution, after some time, vanished irrecoverably. In short, it had all the properties of uric acid in the greatest state of purity. Its quantity, as before stated, was 50 – 4.92 = 45.08; that is to

say, 100 pts. of the excrement contained 90'16 of uric acido

C. The dilute muriatic acid (A) which had acquired a yellowish colour was divided into three equal portions :

1. To the first ammonia was added, so as just to neutralize the acid. This occasioned a very faint cloudiness. Carbonate of-ammonia was now added, which produced no further precipitation

2. To the second portion ammonia was added as before; but ingtead of afterwards adding carbonate of ammonia, the oxalate of ammonia was substituted, which produced a copious white precipitate.

3. The third portion of the dilute muriatic acid was carefully evaporated to dryness. The residuum, after having been accurately weighed, was exposed to a strong heat over a lamp. White dense fumes arose in great abundance, which were muriate of ammonia. After these had ceased to appear, the residuum was again weighed ; and in a mean of two experiments, it was found to have lost -9 gr. Now as ::9 :: 100 : 5:4 parts of muriate of ammonia in 100

3 parts which contained 1.7 of pure ammonia.

II.--A. From I. c. 2, it appeared that the muriatic acid held some lime in solution, but that it was prevented from being preçipitated by the carbonate of ammonia (I. c. l.) on account of the presence of animal matter, which was in a state of intimate unign with it. To determine, therefore, the quantity of this lime more particularly, and also whether any other saline matters were present, 20 grs. of the excrements were burnt in a platinum crucible. The residuum was a small quantity of saline and earthy matters, which weighed 1:36 gr. On this residuum was poured a little distilled water, and heat applied. The water took up the alkaline salts, and was then poured off, and evaporated to dryness. These salts, in a mean of two experiments, weighed 1.20 gr. Acetic acid, on being poured on them, produced effervescence. After this addition, they were again dried, and digested in alcohol. This took up the acetate formed, which, on being decomposed at a red heat, left a quantity of subcarbonate of potash, which weighed 1.01 gr. Now 1:01:X 5 = 5:05 subcarbonate of potash in 100 parts, equal to about 3:45 parts of pure potash.

B. The residuum left by the alcohol was neutral, and weighed •19 gr. It was found to consist chiefly of sulphate of potash, with a trace of a muriate, probably of soda. Now 19 x 5'= :95 parts

X of this mixture in 100 parts of the excrements.

C. Muriatic acid was now added to the residuum (II. A.) pot taken up by the water, which dissolved the whole of it. To this

a

tho

solution was added pure ammonia. A precipitate fell, which was phosphate of lime. On adding carbonate of ammonia, there was a slight precipitate of carbonate of limes - After this phosphate of soda produced a very distinct crystalline precipitate, indicating the presence of magnesia. The quantities of these were too small to be weighed separately, but altogether their weight must have been •16 gr. for 1:36 - 1.20 = .16. Now..16 x 5 = .8,

the quantity of these substances in 100 parts.

D. Lastly, the quantity of animal matter, independently of the
uric acid, destroyed by combustion, was estimated at 2.94 per cent,
For 100 00:16 * 1.7 + 3.45 + .95 + 8 = 2.94.
Hence 100 parts of these excrements contained
Uric acid

90.16
Potash

3.45 Ammonia

1.70 Sulphate of potash, with a trace of

muriate of soda ?
Phosphate of lime
Carbonate of lime

.80
Magnesia ..
Animal matter, consisting of mucus

and a little colouring matter....

of}

.95

2.94

100 Observations, I. c. 2. Oxalate of ammonia will often throty down lime when in a state of union with animal matter, together with the animal matter itself, when other tests will scarcely indicate its presence. This may be verified by almost any secretion from a 'mucous membrane; most of which contain lime united to an'animal matter. For this interesting observation I am indebted to Mr. Wilson. The lime, therefore, in the present instance, was "probably in union as an aliment with an animal matter analogous to mucus, and which was doubtless derived from the internal passages of the animal. It was insoluble in a weak alkaline solution, and "hence could easily be separated by its means. The acid also, as before observed, took up a small quantity of a yellow colouring matter. The quantity of these, however, as estimated above, was probably a little too great, since a small portion of the uric acid was doubtless removed by the repeated washings, which of course caused these matters to appear more abundant than they really were.

I. c. 3. It is extremely difficult to ascertain the quantity of ammonia contained in a substance. I had before observed that this alkali was present, and the above 'mode occurred to me of estimating its quantity. Perhaps it is not very far from the truth, though it can hardly be relied upon as indicating the exact amount.

11.-A. The alkaline matter present was considered as potash, on account of the facility with which its subcarbonate and acetate attracted moisture from the air, and also from its precipitating

a

muriate of platinum. This alkali, as well as the ammonia, I considered as combined with the uric acid, because no effervescence was produced on the addition of muriatic acid.

I obtained these excrements from Mr. Lean, jun. and on ascertaining their composition, went to see the animal said to be the boa constrictor, exhibited near Exeter Change, in order to learn a few particulars of its mode of feeding, &c. This animal is a young one, and, according to the keeper's statement, about 16 feet long. It is fed about once a month only, when a living rabbit, or sometimes two small ones, are exposed within its reach, which, after some time, it seizes, destroys, and swallows, in the manner peculiar to these serpents. The excrements are discharged at periods of about 8 or 10 days, in a softish state, about the consistence of stiff dough; but soon become hard and friable on exposure to the air. They are in the form of roundish scybalæ, and on their surface there is often a yellowish substanice, sometimes in a crystallized state, which crystals I have found to be 'urate of ammonia, tinged with a little colouring matter. These are the only kind of fæces, or excrements, observed to come from the animal. I obtained a portion of them a few hours after they had been discharged, which had all the characters and properties of those above described, which I received from Mr. Lean.

As far as I know, uric acid has not been observed to be formed by this class of animals. Dr. Wollaston has found that birds produce more of this principle when fed on animal matters; and Fourcroy, Vauquelin, and Klaproth, found a large proportion of it in the excrements of a bird called guano, brought from the South Sea Islands.* It is certainly a very extraordinary thing, that nearly the whole of the food taken by this animal should be converted into this substance. May it not proceed from disease arising from the unnatural state in which it is kept?

Liquor Amnii of a Cow. This bad been taken from the uterus of an animal slaughtered in an early period of her gestation. It was of a yellowish colour, and had the appearance of very minute shining particles floating in it. Smell fragrant, something like that of new milk or butter, Taste bland and sweetish, like fresh whey. Foamed a good deal when shaken. Did not affect litmus or turmeric papers. Sp.gr 1.013.

My attention was particularly directed to the principle found in this fuid by Vauquelin and Buniva, and called by them amniotic acid. I could not, however, discover the least traces of a similar principle; but it contained a very sensible quantity of the sugar of milk, which separated in crystals from it, when it had been concentrated by evaporation. It coagulated partially by heat, and

a

a

* I quote from Berzelius's View of the Progress and present State of Animal, Chemistry. P. 103. 108,