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knowlege. Perhaps Mr. Cavendish's continued enquiries, which we expect every moment, may render thefe fubjects more clear. We fhall conclude our extracts with a few remarks from the annotator.
• But whence arifes the aerial acid that appears in thofe phlogiftic proceffes in which animals are concerned? We find it not only in the air that has been refpired by animals provided with lungs, but Mr. Scheele detected it in air in which he had kept infects, and Mr. Achard in common and vital air that had been injected into the cellular tiffue of animals. If it does not proceed from any change of vital air, what remains but that it must be thrown off in fubftance? I would, therefore, propofe this as a proper fubject of experiment, not because I think it calculated to decide the chemical queftion concerning the conftitution of the aerial acid, but because it is a curious phyfiological problem. I know but one fact that has any immediate connection with the folution of this problem, and that is contained in Mr. Achard's paper on artificial emphyfemas. He always found a large portion of aerial acid in inflammable air that had been forced into the cellular tiffue of animals. If it was not contained beforehand in the inflammable air, and little or no common air was introduced along with it, which I think altogether unlikely, the refult feems very much to favour the opinion that fuppofes aerial acid to be an animal emanation.
I know not whether I fhall efcape cenfure for dwelling fo long, both here and before, on the question concerning the aerial acid; but I prefume, with fome confidence, that no one, who is capable of perceiving its extenfive influence on the theory of fo many chemical operations, will blame me with much feverity.'
We once hazarded a conjecture, that the aerial acid might be found to be fome very common fubftance in disguise; and, though we would speak with much diffidence, and hazard a conjecture only, yet there is great reason to suppose, that this kind of air is often a phlogifticated acetous acid. It is pretty certainly known, that it is the acid of ants, which in many refpects resembles the acetous acid; and, in the experiments juft quoted, it may be derived from the acid of fat, which, in Mr. Crell's experiments, produced falts in the fame order, and nearly with the fame properties as vinegar. It may ap pear contradictory to derive an acid fo generally found in foffil fubftances, from vegetables; but it must be confidered, that the aerial acid is often contained in large quantities in the food of vegetables, water, and mould; and that the acetous acid is not formed, but only evolved by the procefs of fermentation. Many fimilar inftances occur in chemistry. There are many other arguments which might be produced, if it were proper:
we omit them, that we may not feem to raise a conjecture to the rank of a theory. Much injury has been done to science in this way opinions are often useful to fuggeft experiments; but they should never fuperfede them, or influence our con. clufions.
The Tables of fimple and double Elective Attraction, both in chemical characters and words, are fubjoined: the latter are highly useful, for Bergmann's characters are not very simple or clear. Yet, as they are now become familiar, more confufion would be introduced by improving than by retaining them.
Filices Britannica; an Hiftory of the British proper Ferns. By James Bolton. 4to. 135. in Boards; 11. 75. coloured. White. THIS
HIS is the firft part of an ufeful and correct defcription of the British ferns, in a moderate compass, and at no great expence.
It is here attempted to bring together and illuftrate the British proper ferns ; no attempt of the kind having ever before appeared in our own, or any other language. The greatest part of them have indeed been figured and defcribed, but many of thofe figures are too inaccurate to give a clear and diftinct idea of the plant, and being fcattered through the volumes of many authors, will fubject to a very great expence, those who are defirous to inform themselves of a tribe of plants fo fingular and beautiful as the British proper ferns must be allowed to be.
It is the intention of the author in this undertaking, to give a clear and diftinct idea of every fpecies in its various ftages of growth, and under the various accidents it is liable to, as far as is neceffary for enabling the ftudent to difcriminate each with eafe and certainty; to exhibit them at one view, and at a small expence...
Mr. Bolton has defcribed and engraven fpecimens of the different British fpecies of ophiogloffum, ofmunda, acrostichum, polipodium, afplenium, pteris, adiantum, trichomanes ; and purposes, in a fubfequent work, to defcribe the equifetum, pilularia, and ifoetis; all the genera of the British Flora. His accounts are, in general, fatisfactory; and the plates, though void of elegance, are clear and accurate. They do not attract the eye by their beauty, but they inftruct the mind by their exactness.
Mr. Bolton has made no alteration in the genera; and, inftead of adding to the fpecies, has degraded many of these, by placing them among the varieties. He feems to have attended very carefully to this clafs of plants; and his obfervations are frequently new, and generally juft. The known va
rieties are more clearly described, and fome of the most remarkable ones are delineated.
The adiantum trapeziforme of Hudfon, Flor. Ang. 460, is fuppofed, with great reafon, to be only a variety of the afplenium marinum. The afplenium trichomanes-ramofum of Linnæus, Sp. pl. 1541, is, in our author's opinion, a variety of the afplenium viride, growing luxuriantly in moist fituations. Mr. Hudson, we perceive, thinks it a variety of the afplenium trichomanes, fince he has inferted the fynonyms of Linnæus under this fpecies.
The afplenium lanceolatum of Hudson is fuppofed to be a variety of afplenium adiantum nigrum, and our author has arranged it in this manner. It is indeed very fimilar to the af. adiantum nigrum; but we have much reason to suspect that our author has actually delineated a variety of the af. adiantum-nigrum, inftead of the af. lanceolatum, fince he has not preferved the specific difference of the lanceolatum, which we have often feen. As he found it fo nearly alike the former, and not very different from the latter, he has perhaps occafioned fome confufion.
It is with more reason that he fubjoins the following remark to the polypodium vulgare.
The polipodium cambricum is now known to be a variety of this plant. The general shape of its leaves oval; lobes confluent, and decurrent at the bafe, irregularly gafhed on the edges, the fegments long, narrow, crouded, ferrated or crenated on the edges, the whole leaf thin, smooth, femi-tranfparent, of a pale green and very elegant. This variety produces no feed-veffels.
There is another remarkable variety in which the lobes are proliferous, having other lobes growing from their fides. This variety was discovered in fructification, in a wood near Bingley, by Mr. W. Alexander, of Halifax, in August 1782.'
We shall infert alfo the following obfervation, to recommend it to the attention of obfervers.
• Polipodium lonchitis very greatly refembles the polipodium aculeatum in fome of its ftates, particularly that variety of it which Hudfon calls polipodium lobatum. Thefe two plants in figure, colour, fubftance, manner of growth, and general habit, bear a resemblance too ftriking to be disregarded.
The polipodium aculeatum and lobatum are found growing on moift rocks and fhady places. Polipodium lonchitis, on the cold mountains of North Wales. Is it poffible that polipodium lonchitis should be a starved variety of polipodium aculeatum ?'
Again, for the fame reason,
I fufpect the polypodium fragrans of Mr. Hudfon to be a variety of this plant (polipodium thelypteris) where the feeds,
accidentally taking root on rocks, produce fmall plants having the parts crouded. Linnæus's defcription of the polipodium fragrans, agrees with polypodium thelypteris in every thing but magnitude. If polypodium fragrans is a real fpecies, I fhall be thankful to any one who will communicate a fair fpecimen, or give hints of information concerning it.'
The polypodium lobatum of Hudfon is, in our author's opinion, a young plant of the p. aculeatum; the polypodium rheticum, a tender one of the p. fragile; and the trichomanes pyxidiferum, a luxuriant variety of the t. tunbrigenfe. We fhall felect the laft remark.
I fufpect the trichomanes pyxidiferum of Bell Bank to be a luxuriant variety of this plant; their figure, texture, colour, and whole habit are the fame, only differing in magnitude. In this opinion I am confirmed by obfervation; for in the year 1784, I found the trichomanes tunbrigenfe growing in great plenty on the rocks under Dolbadon caftle, near the lake of Llhanberris; in cavities where the rock was moist, and overfhadowed with other plants, fo as to exclude the fun, I found fpecimens fo far approaching to the trichomanes pyxidiferum, as to form a connecting link between it and the trichomanes tunbrigenfe, partaking equally of the one and of the other. One of these specimens I have exactly figured.'
Our author's observations on the difficulty of diftinguishing the genera of ferns, in particular periods of their fructification, are very juft; but the inconvenience which has been frequently felt is, we fear, without a remedy. We have little to object to Mr. Bolton's conduct in any respect, except his tranflations of the terms defcriptive of the leaves. Now that we have a fixed English botanical language, it should be strictly adhered to; for, as we have often remarked, it is better to be confiftent in our language, though we fhould fometimes be lefs accurate. In this inftance alfo, the language of the Litchfield tranflators is, we think, preferable.
Jacobi Dickfon Fafciculus Plantarum Cryptogamicarum Britanniæ. 4to. 45. Jewed. Nicol.
HIS work, though small, is almoft wholly new. The author profeffes to enumerate thofe plants only, which are not defcribed by Curtis, Hudfon, or Lightfoot; except in one or two inftances, where, from infpecting the Collections of Linnæus and Dillenius, he has been able to detect some errors, It is indeed both honourable and advantageous to this king. dom and its naturalifts, that we have inherited the learned riches of the Swedish botanist. The plates represent only thofe plants, of which there are no reprefentations in fir Jofeph
Banks's library. They are very faithfully executed; but fome little errors in the references create, at times, a flight confufion.
The first fet of these clandeftine marriages' contains the moffes. The first genus, enriched with new species, is the phafcum. To it are added one under the title of ferratum,' somewhat refembling the p. acaulon of Hudson, Fl. Angl. 466, another ftyled alternifolium, and the third axillare. To the genus fplachnum are added two fpecies from the method. mufcorum, Linn. filii, viz. mnioides & fphæricum: to the mnium one, theofmundaceum.' The bryum viridulum is said to be very different from the b. capillaceum breve, &c. of Dillenus, and mufcus capillaceus, &c. of Vaillant, which are placed as fynonyms under this fpecies by Linn. Sp. Pl. 1584. The b. viridulum is really the Swedish fpecies, as appears from Linnæus' Hortus Siccus; but meffrs. Hudfon, Curtis, and Lightfoot, have been misled by the synonyms, and confounded it with the following fpecies, viz. the b. virens, to which Dillenius and Vaillant's plant is to be referred. Another species of bryum, the ventricofum,' on comparing the herbaries of Dillenius and Linnæus, is very different from the mnium triquetrum, with which it has been confounded. In the whole, Mr. Dickfon has described four new fpecies of this genus. To the genus hypnum, are added the ftellatum, pennatum, ftamineum, and albicans. To the jungermannia, the j. fphagni, angulofa, and pulcherrima: the last is taken from the methodus of the younger Linnæus.
In the order of flags, a different defcription of the genus targionia is added, to include a new species together with the t. hypophylla of Hudson; and another fpecies of riccia is defcribed from the Flora Danica. Eighteen new species of lichen are also described. The 1. canefcens is different from the 1. palefcens of Linnæus, and the fame with the lichenoides cruftofum, &c. of Dillenius; which has generally been fabjoined to the latter fpecies. Of the tremella, three new fpecies appear the t. fabinæ, found also on the juniper, is faid to differ from the defcription of the t. juniperina of Linnæus, in the Flora Laponica.
Among the mushrooms we find ten fpecies of agaricus, moftly new; of the boletus, five; one of which, the b. lacrymans, is the cause of what is called the dry-rot. This plant was known to Hudson, but defcribed by him as a species of agaricus, viz. a. pectinatus. Of the hydnum, there are only two additional fpecies; of the heivella, five; but neither afford any thing which particularly deferves to be noVOL. LXI. Jan. 1786. с