and being, as it is said, its first president (1752), when yet in Shudehill. (It is also said that Mr. Miles Bower was first president, but others must settle that point.)

These Masseys were evidently men of wealth and of weight, with intellectual and benevolent tendencies.

In the MSS. there is mentioned as present at the second meeting of the Society Mr. John Massey.

Mr. James, the president, had some knowledge of chemistry, and his paper seems to indicate having been abroad. It is a good specimen of the thinking of the time, and we shall give a pretty full extract.

A Treatise on Saltpetre, by James Massey, Esq.

P. 188. 'Saltpetre, to give a just description of it, is a neutral saline concrete, evidently formed by a combination of a peculiar acid with a fixed vegetable alkaline salt. This acid is found in certain earths, from which it is extracted, by elixiviating them along with wood-ashes, the fixed salt of which, uniting with the acid, forms this neutral one, which crystallises in the ley when boiled down to a due consistence.

'From this plain account of the formation of saltpetre, it must be obvious that it can nowhere be found without the concurrence of these two principles; and, consequently, not in the air, or in vegetables or animals, because, though this peculiar acid may perhaps be found in these subjects, the fixed salt must needs be wanting.

'That it may be sometimes found in the earth we shall not deny, owing to the accidental introduction of wood-ashes to a soil impregnated with this acid. And that from hence it may pass into the stems and apices of

some plants, with the moisture that enters their roots, is far from being improbable. But that whole provinces can even be covered over with it, or that it can be generated in these organised bodies, as Lemeri and some others have imagined, must exceed all belief.

'The accounts which travellers generally give us of this salt are, that it is extracted from the soil of the countries they have visited, by elixiviating it with water, and evaporating the fluid; which we believe may be consistent with truth; but here it should not be forgotten that a certain portion of wood-ashes is always added to this soil before it is elixiviated, a circumstance which, either through ignorance or inattention, they have too often omitted to

mention.'

P. 190.

P. 190. Of these earths the most distinguished are, the rubbish of old houses, the ruins of old vaults and cellars, &c., which rarely fail to yield us the crystals of this salt when elixiviated with wood-ashes. That these earths possess an acid quality is not to be disputed; seeing that upon reducing them to a coarse powder, and percolating a fixed alkaline solution through them, this solution will be neutralised, and no longer yield us an alkaline, but a neutral salt.'

P. 191. From the well-known fact, that the rubbish of all such houses as have been occupied by the filthiest inhabitants, and of such clay walls as have stood in the neighbourhood of dunghills, or wherever putrid vapours more plentifully abound, is always most strongly impregnated with this acid, it is most natural to believe, that these vapours must confer it upon them, and consequently, that it must

have its origin in putrid substances; but to this there are likewise many objections. In the first place, the recent juices of vegetables and animals, some few of the former excepted, if we are not mistaken, contain no kind of acid whatever, and in a putrid state everybody knows they are of a volatile alkaline nature, which being the most powerful objection, we shall here principally endeavour to remove, and upon the whole shall undertake to show that there is an original acid in all vegetables and animals, which being rendered volatile by putrefaction, assumes the specific character of the nitrous. And that, since this acid constantly arises in vapour from putrid substances, hence it is that the rubbish of old houses, and of old clay walls, become impregnated with it, as well as those earths that lie in conjunction with them.

'That the recent juices of vegetables and animals are in general perfectly neutral, we shall readily admit; but from hence we think it does not follow that they contain neither an acid nor alkali, as is commonly concluded; on the contrary, we apprehend a more just inference is that, being mixed, they must necessarily contain both. It is certain that if we throw a calcareous earth or fixed salt into any of these juices, the earth or salt will be neutralised by it; which we take to be a proof that it contains an acid, which quits the weaker to join with the stronger alkali, according to the law of affinities.

'And the case will be the same, if these juices are putrefied. If we throw a fixed salt into any putrid liquor it will be neutralised by it, and now, if we dip a piece of soft paper into this mixture and dry it, it will burn like a match, in the same manner as if dipped into a weak solution of saltpetre; which shows, that it not only contains

an acid, but one of the nitrous sort; and provided this liquor were putrefied, and the marine salt, with which all nitrous leys greatly abound, carefully removed, we cannot help thinking that upon being boiled down to a due consistence it would yield the crystals of saltpetre. The author must acknowledge he has boiled down many of these mixtures without success: but it was at a time when he was ignorant of the necessity of attending to the above circumstances.

That all putrid substances, and consequently their juices, are of a volatile alkaline nature, is not to be denied, owing to an union of their acid and oily parts with their earth, which is equally subtilised by the putrid process.'

P. 193. But the strongest proof of the existence of an acid in putrid juices, if the earths of stables and cow-stalls do not afford an equal one, must be drawn from the soil at the bottoms of graves, which can certainly derive its nitrous acid quality from nothing but the corrupt bodies with which it lies in contact; and this may satisfy us in respect to the source from which other absorbent earths may derive it.

'Other earths, in common use among the saltpetre makers, are those of stables and cow-stalls, that have drunk up much animal urine; the bottoms of stinking pits and ditches and the like. These they take out and lay in heaps, till by repeated trials they find them fit for their purpose. It is commonly supposed that, during this period, they draw their nitrous quality from the air; but for this there is certainly no just foundation, seeing they are brought to maturity as soon in the closest vault or cellar as in the most open exposure. The truth is, that all putrid juices

contain many oily and mucilaginous parts, which, till they are duly attenuated by putrefaction, will not suffer any crystals to form in the leys that are drawn from these earths; and they are laid in these heaps for this event to take place.

'The ingenious author of the " Chemical Dictionary" has told us, that the nitrous acid is nowhere found but in such earths as are impregnated with the juices of vegetables and animals, and where these juices have sustained the whole putrefactive process. But having assigned no reason for it, he seems to have been little regarded.

"The common soil in some parts of India is naturally nitrous, owing plainly to the fish and slime that is left upon it by the inundations of the river Ganges, which soon corrupt in that hot climate, and fill the earth with putrid juices; and here putrefaction, being carried on with the greatest rapidity, is, of course, soon completed, and the natives are, in a short time, furnished with a nitrous earth perfectly matured. But it must not be forgotten, that their strongest earths are found at the bottoms of their tanks or shallow ponds of water, which, in this country, are often of great extent, where, the water being evaporated by the heat of the sun, large quantities of fish are left to corrupt, which furnish a mud of the strongest nitrous quality.

In this manner are nitrous earths naturally formed in these parts of the world, and might doubtless be formed. in others, though not perhaps so expeditiously, by throwing into shallow ponds of water, natural or artificial, all sorts of dung and carrion, with other putrid and putrefiable matters; where the water, being evaporated by the heat of our