most of them are so acid as to curdle milk, yet this is not altogether universal;. and though in many of them the acid is so far enveloped in their solid contents as to ferment with alkalies, this appearance is not always conspicuous; whence one would imagine, that the milder sort might be used with more freedom, or less danger; and yet it is certain, that one of the sharpest of them all, viz. that of Kilbrew, in the County of Meath, has been taken inwardly, with success, in some very stubborn cases.

Yet, on the other hand, it has been observed, that even the German Spa sometimes has proved too irritating in some tender constitutions, where our ordinary milder chalybeates have succeeded well; and he was informed by an accurate observer that, in some tabid cases, particularly that called the galloping consumption, the mildest and lightest of our own chalybeates, even though blended with milk, have been found to increase the hectic heats and tension of the pulse. Now, this observation seems not easily reconcileable to another of Dr. Horseburgh, in the place above-mentioned, on the Hartfell spa (a much stronger and harsher chalybeate than either the German spa, or any of our ordinary chalybeates) viz. that it has actually been given, with notable success, from half a pint to a pint a day, in consumptions of the lungs, far advanced, even attended with hectic heats and night sweats. So memorable a fact, in the cure of a deplorable disease, deserves attention; and the Scotch physicians in that neighbourhood are called on to corroborate it by further observations; as how long those cures stood, and how far they may have been confirmed by the like success in similar cases; whether used with or without milk; and lastly, whether, as an acid austere medicine, they may cool, correct, and give a better consistence, in a colliquative state of the blood; seems well to deserve further inquiry, and that the result should be communicated for the public utility.

There had indeed formerly obtained a general prejudice against the use of the ordinary chalybeates in diseases of the lungs; but, at length, experience has convinced us not only of their safety, but usefulness, and good effects, especially when tempered with milk, in many of those cases. And moreover, it is but doing justice to our acid vitriolic waters, to acknowledge, that the empirical trials made on them by the giddy vulgar, have been frequently such as demonstrate, not only their safety, but even powerful effects in other rebellious disorders; as, particularly, the Kilbrew water (one of the sharpest and most strongly saturated with martial vitriol of all these waters yet discovered) in the notable cure of an ascites, complicated with a jaundice, which Dr. R. had elsewhere related; and he saw no reason why physicians should not, in this as well as other cases, avail themselves of the happy success of such casual experiments. In order, therefore, to promote a view of this kind, and, as these vitriolic waters are better adapted for use than the ordinary chalybeates, as bearing carriage to remote places, and may be kept fit for use at all seasons of the year, and

are to be preferred in medical intentions, whenever the strongest of the chalybeates are required, and can be borne; he here, from facts and observations made on the several waters of this sort, which had fallen under his notice, gives a short sketch of their general operation and good effects, as a foundation for further improvements.

These waters, then, generally operate as an emetic or cathartic, or both; and have recommended themselves, in external and internal use, as a powerful detergent, repelling, bracing, styptic, cicatrizing, antiscorbutic, and deobstruent medicine, as has appeared by the notable cures they have effected, not only by external use in inveterate ulcers, the itch, mange, scab, tetterous eruptions, scald head, and sore eyes; but also by internal use in hot tetterous eruptions, dysenteries, internal hæmorrhages, in gleets, the fluor albus, and diarrhoea, in the worms, agues, dropsies, and jaundice.

Such has been the success, that has not unfrequently crowned the empirical use of these waters; which, though in some of these cases, it might undoubtedly have been better conducted in the hands of the prudent physician, may however suffice to convince us, that the vitriolic waters are a branch of the materia medica, not to be despised nor overlooked, in the cure of chronical diseases.

many stubborn

XLVI. An Account of that Part of America, which is nearest to the Land of Kamtchatka; extracted from the Description of Kamtchatka by Professor Krashennicoff, 2 vols. 4to. Petersburg, 1759. p. 477.

As accounts (and some of them taken from later navigators) of the part of America here mentioned, are to be found in every modern system of geography, it was deemed unnecessary to reprint this paper.

XLVII. Remarks on the Mutations of the Stars. By Tho. Barker, Esq. of Lyndon, in Rutland. p. 498.

It is well known that there have been several alterations among the fixed stars: for instance, Ptolemy's ultima fluvii, a first magnitude star, is in Dr. Halley's catalogue of the southern constellations only a 3d magnitude: and in much less time, the ♪ of the Great Bear, which Bayer seems to have judged just of the same size with the other 6, is become far duller than any of them. Some stars also have quite disappeared, while again new ones, not seen before, have been discovered; and there are others periodically larger and smaller. Two very remarkably bright, yet short-lived stars, have been also seen, one in Cassiopea, the other in Serpentarius; which breaking out at once, with greater lustre than any other fixed star, gràdually faded, and changing to different colours, in about a year and half were no longer visible. But no one has yet remarked that any lasting star was of a different colour in different ages; Greaves, on the contrary,

takes notice, that the colours of the stars and planets are the same now as the ancients observed, which is very true in general; for Ptolemy, in his catalogue of stars, says, Arcturus, Aldebaran, Pollux, Cor Scorpii, and Orion's Shoulder, with another to be mentioned presently, are oxippos, reddish: and the 5 here mentioned are still of that colour, and probably the only considerable stars which

are so.

But to this rule there seems to be one exception, and that in a remarkable star: for old authors mention the Dog star, which is now white, and not at all inclined to redness, as being then very much so, as in many passages of their works.

Hyginus, in distinguishing Canis from Sirius as two different stars, seems to contradict all other writers, who speak of them as one, except perhaps two or three latter ones, who directly quote Hyginus's words. Sirius, or Canis, the brightest star in the heavens, is that which Ptolemy calls in the mouth; Eratosthenes and Hyginus, in the tongue; but whether Bayer y, which Flamsteed calls a 3d magnitude star, Ptolemy only a 4th, was in more ancient times larger, Mr. B. will not pretend to say; since Eratosthenes and Hyginus both speak of two stars in the Dog's head, as thought worthy of particular names. If in Hyginus, flammæ candorem means the whiteness of its light, as candor often does, he expressly contradicts what is mentioned by others; yet still thinks Ptolemy's authority seems greater than that of Hyginus. But candor is also used for innocence, beauty, brightness, &c.

However in most places candor is used in the same sense as in Hyginus, for brightness, without regard to colour; for so he must be understood, not only to avoid contradiction between him and Ptolemy, but from the name Sirius, which it could not be called from its whiteness, Lipios bearing no relation to that, but to brightness, heat, or dryness; all which the ancients speak of as properties of the Dog star. Again, it is brightness wherein it excels all other stars, and not in whiteness; for Orion's foot and others are as white, but there is none so bright as the Dog star. All this is said on supposition there was but one remarkable star in the Dog's head, that in the mouth; for if there were two, as Hyginus says, we are not here concerned with either the brightness or colour of his Sirion, which was in the head, as it certainly faded before Ptolemy's time, who mentions only one, that in the mouth, and which, he says, was then red, but is now white.

XLVIII. The Method of making Sal Ammoniac in Egypt; as communicated by Dr. Linneus, from his Pupil Dr. Hasselquist, who had been lately in those Parts. By John Ellis, Esq., F. R. S. p. 504.

Sal ammoniac is made from the soot arising from the burnt dung of four3 K

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footed animals that feed only on vegetables. This dung is collected in the first 4 months of the year, when all their cattle, such as oxen, cows, buffaloes, camels, sheep, goats, horses, and asses, feed on fresh spring grass, which, in Egypt, is a kind of trefoil, or clover; for when they are obliged to feed their cattle on hay, and their camels on bruised date kernels, their excrements are not fit for this purpose; but when they feed on grass, the poor people of Egypt are very careful to collect their dung quite fresh, and for that purpose follow the cattle all day long, in order to collect it as it falls from them; and if it is too moist, they mix it with chaff, stubble, short straw, or dust, and make it up in the form of cakes, about the same size and shape as it lies on the ground. Then they fix it to a wall to dry, till it is fit to be burnt.

For want of wood, which none but the rich in Egypt can afford to buy, they burn this dung through the whole country, and sell a vast quantity of it to the salt-makers. The excrements of the camel are not found at all preferable to any other; and its urine is never used for this purpose, though generally reported so by authors. The salt-workers pretend that the human excrements, and those of goats and sheep, are preferable to any other. The months of March and April is the only time they make the salt.

Sal ammoniac is made in the following manner: They build an oblong oven, about as long again as broad, of brick and moist dung, of such a size that the outside, or flat part of the top of the arch, may hold 50 glass vessels, 10 in length, and 5 in breadth, each vessel having a cavity left for it in the brick-work of the arch. These glass vessels are globular, with a neck an inch long, and 2 inches wide. They are of different sizes, in different salt-works, containing from a gallon to 2 gallons: but in general are about 18 inches diameter. They coat each vessel over with a fine clay, which they find in the Nile, and afterwards with straw; they then fill them full of soot, and put them into their holes on the top of the oven.

They make the fire gentle at first, and use the afore-mentioned dried dung for the fuel; they increase the heat gradually, till they bring it to the highest degree, which the workmen call hell-fire, and continue it for 3 days and 3 nights together. When the heat is come to its due degree, the smoke shows itself. with a sourish smell, that is not unpleasant; and in a little time the salt sticks to the glasses, and covers the whole opening, The salt continues subliming,. till the above-mentioned time is expired; then they break the glasses and take out the salt, just in the same form, and of the same substance, that it is sent all over Europe. At each salt-work they have a glass furnace to melt the old glasses, and make new ones.

XLIX. Montium quorundam præaltorum, magna ligni fossilis copia quasi infarctorum, brevis descriptio Sam. Christ. Hollmanni, Phil. Professoris Goettingensis, et S. R. Sodalis. p. 506.

In this paper it is stated that immense quantities of fossil wood are found in the lofty mountains situated in the confines of Hesse and the principality of Goettingen.

L. Experiments in Electricity: in a Letter from Father Beccaria, Professor of Experimental Philosophy at Turin, to Benj. Franklin, LL.D., F. R.S. p. 514. To be read improved in the published works of Fa. Beccaria.

Remarks on the preceding Paper. By Benj. Franklin, LL.D., F.R.S. p. 525.

For the better understanding this paper, it is necessary to know that Father Beccaria uses a large chain, suspended by silk lines, for the purpose of a prime conductor; and that his machine for turning the glass globe is so contrived, as that he can, on occasion, readily isolate it, i. e. place it on glass or wax, together with the person that works it. When the communication is thus cut off between the earth and the chain, and also between the earth and the machine, he observes that the globe being turned, both the chain and the machine show signs of electricity; and as these signs, when examined, appear to be different in the chain and in the machine, and the globe having, as he supposes, drawn from the machine part of its natural or common quantity of electricity, and given it to the chain, he calls the electricity appearing in the chain, electricity by excess; and the electricity appearing in the machine, electricity by defect; which answer to our terms of positive and negative electricity, or electricity plus and minus. And thus his expressions, electrifying by the chain, and electrifying by the machine, are to be understood, electrifying positively, and electrifying negatively.

Ll. An Uncommon Case of an Hæmoptysis. By Eras. Darwin, M.D. p. 526. A gentleman residing near Litchfield, between 40 and 50 years of age, of a pale and meagre habit, had been daily afflicted with violent head-aches for several years; and, about 4 years before, after having taken a considerable quantity of Peruvian bark, became suddenly paralytic. The use however of his right limbs was so much restored as only to remain weaker than the other; when, on suddenly awaking from his sleep about 2 o'clock in the morning, May 7, 1759, he spit up 4 or 5 oz. of florid blood. He immediately lost 12 or 14 oz. from the arm, had elixit of vitriol given him, and in the evening had a clyster, and lost blood again to about 10 oz.

On the 8th, about the same hour, he again suddenly awaked, and spit about