should contain accurate descriptions of those minutie, which, though necessary to be known, are usually omitted in elementary works, would be a valuable gift to society. To supply, in some degree, this deficiency, was the object of Dr. Ewell in composing the work before us. He professes, in the preface, to give a general account of the properties of matter, with more particular details of the most useful and interesting parts of the science, in a language, adapted to the comprehension of the most common understandings.' Its object is to lessen the difficulties and increase the conveniences of the citizens of the United States, by introducing them to a more intimate acquaintance with chemistry, or the qualities of the substances around them.' He acknowledges his obligations to the various systematick works of Thompson, Murray, and Accum; but, says he, it will be found, that I have advanced something new on the subjects of heat, light, electricity, vegetation, manures, and on several other branches of chemistry.' In common, however, with many other authors who have prejudged the publick sentiment, Dr. Ewell has informed us, that an allowance should be made for the errours of the work, by considering, that it was written in the moments of leisure, in the intervals of professional avocations. It is of little consequence, however, to his readers, whether it was composed in broad day, or by the midnight lamp; in the hours appropriated to business, or during the moments usually devoted to relaxation and social enjoyment. A work will be ultimately estimated by its intrinsick merit. It may be, for a while, upheld by the patronage of the friendly, or supported by the clamours

of the interested, but it will eventually sink to its proper level, and rest on its own worth.

The preface is followed by an address to the farmers, artists, and other citizens of our own country, in which are detailed at large the various arts, whose operations depend on the agency of chemical laws, and the extensive application of the principles of this important science to the purposes of life. The account is well written, and is calculated to give his readers a correct idea of the immense variety of operations, which are founded on the doctrines of chemical affinity. But in speaking of the pleasures, which the chemist enjoys in the contemplation of the effects of these laws, our author quits the sober style of science for the la guage of the visionary. Here, 1. fact, commences that rage for "something new," by which the subsequent pages of this work are characterised. We could not help smiling at the affected stoicism, with which he utters the following curious sentence, in attempting to describe the last moments of a chemist: Instead of trembling,' says he, on finding his extremities losing their genial warmth, and growing dark with livid fluids; instead of giving way to shrieks and lamentations, while his perception is failing, his mind may be amused in contemplating the exercise of the laws of his visible body, till it takes a final departure for enjoy. ment in other scenes.' ever, is merely the commencement of the climax, which is at length unfolded in the last page of this address, where our author steps forth, arrayed in all the terrours of inspiration, in the following sublime passage: Ye free agents! ye guardians of the young! can you allow those under your care to

This, how

neglect learning the principles of this all-important science! What then will you say, when arraigned at the bar of justice, before a Creator, an assembled universe; for neglect of duty? Your hoary locks will not cover you! the number of the accused will naught extenuate, and in vain will you deny the charge! The children of successive generations will rise up around you In the face of heaven they will bitterly complain of the beauties, to which they were insensi ble! At this awful denunciation, we confess, we were somewhat startled

Steteruntque comæ et vox faucibus

hæsit.'

The substance of the work is comprised in fifteen discourses, in which our author has pursued the subject systematically, and has a dopted an arrangement that is well calculated to give a correct view of the objects of this science. He first divides all bodies into confinable and unconfinable. The latter term he applies to the four elements, heat, light, electricity, and galvanism. Under the former are included, first, the aëriform or gazeous fluids, and the various liquid bodies, resulting from their union. -2. The simple combustibles and the products, arising from their combination with oxygen.-3. The simple or undecompounded acids. —4. Alkalies.—5. Earths.-6. Metals.-7. Vegetable, and, 8. Animal chemistry. The whole is concluded with an address' to his fellow-citizens.

We shall now proceed to examine the work itself. A new and original production on any subject of science, is such a rara avis in this hemisphere, that we opened the leaves of this work with a sufficient degree of prepossession in

its favour. Our curiosity, however, was somewhat checked on the perusal of the observations, prefixed to the account of the unconfina ble bodies. We are told, in the title-page, that this work professes to discourse on the laws of matter, and hence we are led to expect, that it ranges through the whole circle of physical science. Yet, in the first paragraph, we are presented with a definition, or rather explanation, of the science of chemistry. The object of chemistry,' says he, being to ascertain the properties, or qualities, or laws of matter, it follows, that every thing around us, commencing with the air, and ending with the earth, are the subjects of chemical research.' Dr. Ewell surely cannot be igno rant, that by this observation, which in the table of contents is called a definition, he confounds this science with mechanical philosophy and natural history. The distinc. tion, however, between these departments of physical science is very obvious, though the precise boundaries of each may not have been exactly ascertained. Natural philosophy is employed in the investigation of those effects, which result from sensible motion.* The return of a body to the earth, when deprived of the power by which it was elevated, depends on the operation of an unknown law or power, inherent in matter, called, by Sir I. Newton, gravitation; which is simply an expression of an ultimate fact, beyond which the most acute mind is lost in uncertainty. ratio of the momentum of this body, or in other words, the inten sity of the power, is determined on mathematical principles, and the effect is referred to the doctrine

The

* Henry's epitome of chemistry. In troduction.

of moving forces. When an elas tick substance impinges on another at rest, the latter acquires some principle, by which it is caused to change its place. These actions, though resulting from the operation of certain laws of matter, are obviously not chemical. The construction of achromatick glasses depends on the different degrees of refrangibility of two species of that substance; and the laws, by which they are regulated, make a part of dioptricks. The formation, however, of these substances, the nature of the ingredients, and the theory of their reciprocal action, result from the application of laws, which are strictly chemical. On the other hand, the province of natural history is to describe the qualities of bodies, and, according to their degrees of similitude in external characters, to reduce them to certain classes, and subdivide them into genera and species. But neither the naturalist, nor the mathematician, nor the natural philosopher, has any thing to do with those actions, which, in certain circumstances, result from the contiguity of heterogeneous particles, and are followed by a change of properties and relations. We thus approximate to the true definition of chemistry. But it is not our duty to supply, though it may be to expose, the deficiencies of Dr. Ewell. From this view of the subject, it will appear obvious, that our author has given an erroneous statement of the nature of this science, by confounding it with those, which treat only on the general properties of matter. Having thus, as he supposes, established the definition of chemistry, he devotes a few pages to the consideration of the general laws of matter, in which he briefly notices the attractions of gravity and cohesion, chemical af

finity, and repulsion. The doctrine of affinity is the most important, and the most interesting, in the whole range of chemistry. In fact, to know the affinities of bodies, is to be acquainted with the science; and we have a right to expect, therefore, in a work like this, that the laws, by which they are regulated, should be accurately detailed and clearly arranged. But we look in vain for this generalisation. The account, we think, is confused and imperfect, and by no means calculated to give its readers a correct idea of its importance. Dr. Ewell, however, is an enemy to divisions, and we cannot expect them in a work, whose author declares them opposed to the uniform simplicity of nature.' On repulsion he has said little. In fact, he has altogether denied the existence of a repulsive principle among the particles of bodies, and endeavours to support his opinion by this sage observation that the cause of the separation of such bodies is a mechanical one, as in most cases will appear evident, and consequently it would be improper to conclude there is a repulsive principle. p. 50.

Our author then proceeds to describe the nature and principles of those elementary substances, to which has been applied the term unconfinable. The first of these is heat. We could not help remarking the want of arrangement, in describing the various relations of caloric. The fears of Dr. Ewell, that his subject would be rendered perplexed, by many subdivisions, have led him into an opposite errour; and the account, therefore, of this substance, seems both confused and imperfectChemists have usually divided caloric into two kinds, viz. of communication, and of transmission, or

radiation. Of the latter, however, he has said nothing. In fact, he seems not to have been acquainted with the experiments of Mr. Leslie, and of Count Rumford,† on the different radiating power of the surfaces of different substances, although on this principle have been founded important improvements in various arts, essential to the comfort of society. On the various conducting powers, of different substances, and the application of this knowledge to the purposes of life, Dr. Ewell has written with accuracy and judgment, although here, as in many other places, we remarked the copious extracts from the chemical work of Mr. Accum. But, while considering the various modes of generating or evolving caloric, we were not a little surprised to find, that the heat, produced by the appulsion of the solar rays on terrestial bodies, should be considered as the effect of chemical action. We are told,§ that the caloric, generated by bringing the rays of the sun to a focus, by a convex lens, is in consequence of the union of light with the particles of bodies, by which their capacity is destroyed, and their latent heat consequently evolved. In proof of the correctness of his opinion, he affirms, that it requires some time for the rays of caloric to pass through the substance of the glass. It is well known, that caloric is at first retarded in its passage through diaphanous bodies, in consequence of combining with their particles. At least, this is the fact with regard to the radiation of the particles of this substance from culinary fire, though the retardation of solar heat is by no means so obvious.

Leslie on heat.

† Nicholson's Journal, 8vo. series. Accum's Chemistry, vol. 1, p. 88. Page 67.

But let us for a moment suppose, that bodies, placed in the focus of a burning glass, are not acted upon by the calorific solar rays, it may still be asked, in what way can light act by evolving their latent caloric ? When metallic, or concrete oily substances are thus exposed, they are soon reduced to a state of fusion, their capacities are increased, and they consequently absorb caloric; yet Dr. Ewell is made to say, that bodies, exposed to the rays of the sun, have their capacities for heat increased, and consequently are made to evolve the caloric, with which they were combined. This is evidently an absurdity; for it is impossible to conceive, that the fluidity, and consequent increase of capacity of a body, could be produced by the evolution of a quantity of caloric, which was just sufficient for it in a solid state. Our author endeavours, in the same way, to account for the fusion and combustion of different substances, by the electrick and galvanick fluids, not recollecting that their capacities for heat are probably diminished by the sudden and violent compression of their particles.

In the subsequent pages we find him attacking the theory of latent heat, as described by Dr. Black. He however quotes no authorities, nor has once mentioned the names of Crawford and of Irvine, who are so justly celebrated for their writings on the capacities of bodies. But we shall have sufficient reason to believe, that respect for the opinions of others is not to be ranked among the infirmities of Dr. Ewell. It is quite unnecessary,

we presume, to enter on the discussion of the different theories,' which have been advanced by several philosophers on the nature of capacity; we shall, therefore, con- . fine ourselves to the examination