Muriate of lime, and muriate of magnesia, in nearly

2

2. The mother liquor, or brine that remains after separating all the common salt, which it is thought worth while to extract, had the specific gravity of 1208. The dry salt contained

3. The clearings of the brine, which are raked out of the pan when the salt first begins to granulate, contained in 1000 parts,

Muriate of soda
Carbonate of lime

Sulphate of lime

800

4. Of the substance called by the workmen pan-scale, two specimens were analysed, the one containing a large proportion of muriate of soda, the other very little. The first variety consisted of

Circumstances, however, are constantly occurring to vary the proportion of ingredients, both in the clearings and in the pan-scale. If, for example, the brine be short of the point of saturation with common salt, it acts, when admitted into the pan, upon the muriate of soda which the pan-scale contains, and we obtain the second variety. But if the brine be fully charged with salt, it effects no solution of the muriate of soda, carried down along with the gypsum; and then the first species of pan-scale results.

5. The salt oil, or mother liquor from sea water, a specimen of which I received from Dr. THOMSON, had the specific gravity of 1277. It was abundantly precipitated by muriate of barytes: by pure ammonia, but not by the carbonate; and was not changed by oxalate of potash, either immediately or after an interval of some hours. One thousand parts of the dry salt consisted of

6. The salt brine, or liquor which drains from the Scotch salt, had the specific gravity of only 1188. It was affected by the same tests as the salt oil, but less remarkably. The dry residue contained

7. The mother liquor, or bittern pan Lymington, presented, on analysis, an unaccountable variation from the similar fluid sent from Scotland, and gave a much larger proportion of sulphate of magnesia. A considerable quantity of this salt had, moreover, crystallized in the bottle which contained the liquid. Its specific gravity was 1280. One thousand parts of the dry salt contained of

From the very near approximation of the proportions between the sulphate of barytes and ammoniaco-magnesian phosphate, obtained in the analysis of all these products of sea water, to those which result from the decomposition of

The proportion of these carbonates I was prevented from determining by an accident.

two equal quantities of sulphate of magnesia, it may be inferred that they contain no sulphate of soda.* For example, to decide whether the Scotch salt contains an alkaline sulphate, or not, I dissolved 1500 grains in a pint of boiling water, and evaporated till fourteen drachm measures only remained, the common salt being removed as soon as it was formed. The residuary liquid was divided into two equal portions, one of which gave 18 grains of sulphate of barytes, and the other, 14 grains of ammoniaco-magnesian phosphate. The proportion between these numbers is so nearly that which has been already assigned, (viz. 112 to go,) that we may safely infer the total absence of sulphate of soda. This salt, indeed, is considered as incompatible with muriate of magnesia; but after digesting, for two or three days, 100 grains of the former, with 20 of the latter, evaporating to dryness, and washing the residuum with repeated affusions of alcohol, I found that two grains of the muriate of magnesia had escaped decomposition.

⚫ I employed more attention in investigating the presence of sulphate of soda in the products of sea water; because this salt is stated to be one of its ingredients by the Bishop of LLANDAFF, (Chemistry vol. ii. p. 62,) and by other chemical writers.

Manchester,

June 19, 1809.

V. Description of an extraordinary Human Foetus. In a Letter from Mr. Benj. Gibson, Surgeon, to H. Leigh Thomas, Esq. F.R.S.

DEAR SIR,

Read February 8, 1810.

Manchester, June, 1809.

I HAVE lately had an opportunity of inspecting a singular human fœtus, at the full period of utero-gestation, and hope that a history of it will not be unacceptable to the learned Society, of which you are a member. Some deviations, which it exhibits, from the usual form and structure of the human body, have not (as far as my information extends) been yet recorded; and the consideration that they were all apparently compatible with life, gives additional interest to the subject; for if the difficulty of parturition had not proved almost immediately fatal, the complex structure of the animal would have formed no impediment to its existence.

Instances of two entire human bodies united together, are by no means rare in the collections of anatomists. Sometimes their conjunction takes place back to back; sometimes the reverse; at other times side by side; or in such a position as to form a kind of cross: the two heads lying in one direction, and the opposite extremities in another, and intersecting it at right angles.

That species of monstrosity, however, in which two bodies are merely united together, does not display in a striking