receiver. Sometimes it is convenient to have it constructed as in Fig. 2. In this there is an additional tube, B, in order to increase the distance between the retort and the receiver. The upper part of the retort has also an opening, and is supplied with an air tight glass stopper, at which the first portions of air or gas may be permitted to escape when necessary. In some cases of distillation, the product is not only a gas or vapour, which condenses, but also an elastic fluid, which is incondensible. To provide for this case, the receiver is supplied with a bent tube, C; the condensible product is then collected in the receiver, and the incondensible product passes through the tube, and is either allowed to escape, or is collected by the end of the tube being carried into a pneumatic trough, in the manner before described. Fig. 3 is a representation of one of the most approved adaptations of what is called Woolfe's apparatus. The use of this is to obtain a product not condensible by itself, but which may be condensed by coming in contact with water, or by being transmitted through it. It consists of a series of glass globes, from each of which a tube issues straight at the neck, so that it can be fitted by grinding into another globe, but having such a curvature, that the extremity of it dips into the liquid contained in the globe into which it enters. A retort is adapted to the first globe, which is designed to collect the condensible part of the product. Water is put into each of the other globes, as high as the dotted lines; and the neck of the globe passing into this water, transmits the gas through it, which is thus absorbed. Any gas which is not absorbed, passes off at the bent tube at the end, and may be collected in the ordinary way. In the second globe, is what is called a tube of safety. This apparatus requires no lute; and has this advantage, the retort may be removed at any stage of the process, to weigh what has been lost.

In general, heat is applied to the retort by means of a sand-bath, which consists of sand heated to any requisite degree, or by means of a water-bath. A greater heat may, however, be applied, if a proper retort is used. This is a very useful apparatus, as, in many chemical experiments, more than one, two, or three products are obtained, which are thus, according to their properties, condensed in the first globe, combined with water, or condensed, by its means, in the others, or passed off into the pneumatic trough, and there collected or suffered to escape altogether.

MR. GURNEY v. THE QUARTERLY JOURNAL OF SCIENCE.

In

LAST year Mr. Gurney published "A Course of Lectures on Chemical Science, as delivered at the Surrey Institution, which was reviewed in the 32d Number of the Quarterly Journal of Science in such a manner as to excite his displeasure. answer to the Review, he has published a small pamphlet, under the title of a Letter to W. T. Brande, Esq., the Editor of the Quarterly Journal, and Professor of Chemistry at the Royal Institution, where the Quarterly Review is edited. In this letter Mr. Gurney attributes the severe strictures of the reviewer to a wish, on the part of certain persons connected with the Royal Institution, to crush him. On this point Mr. Gurney has probably overrated his own importance; and, imagining himself in opposition to certain distinguished Chemists, has attributed an hostility in them to rising genius, utterly unworthy of their talents, and by no means called for, either by the novelty or value of his discoveries. Without entering into the motives of either party, we feel ourselves bound, for the honour of the science we cultivate, to mingle in the dispute between him and the "Quarterly Journal." We are unacqainted with both parties, and only wish, on the one hand, to protect the science from an inundation of false theories; and, on the other,

to prevent an individual from being put down, merely because his views are opposed to those of some scientific sect. We have read enough to know that few theories are incontrovertibly established; and whenever we find persons more tenacious of supporting a particular set of doctrines than of eliciting truth, and more clamorous than rational in argument, we are led to believe that they begin to suspect the correctness of the system they defend.

The complaint of Mr.Gurney, putting aside what he says of improper motives, is, that his "Lectures on Chemical Science contained some views which were both novel and important; that the Reviewer, after announcing his intention to take notice of these views, pretends not to understand them; and thus vilifies what he should have shown to be erroneous before condemning; that he makes garbled extracts, misrepresents passages, and has altogether given an unfair review of the book." If these charges are substantiated, such a proceeding, from whatever motive it may have arisen, is quite unworthy of the Journal which pretends to be the first scientific Journal of this empire. Of course, the first part of the charge implies that Mr. Gurney has made some important additions to our knowledge; and he points to his third Lecture, as containing a novel and juster theory of crystallization than has before been published. If it cannot be shown that Mr. Gurney has made such an addition to our knowledge, all his remarks against the Reviewer fall to the ground.

If we understand his discovery, it is this :-Dr. Wollaston, Haüy, and others have assumed that the primitive molecules of matter have three original distinct forms. "No," says Mr. Gurney, “ they have only one; and I will undertake to show how all the phenomena of crystallization may be accomplished, and all the various forms of crystals produced, by all the elementary substances, or atoms, or molecules of matter having only one form,

com

and that form the most simple possible, namely the sphere. It is a fact, admitted both by Mr. Gurney and his opponents, that to form compound bodies, the primary atoms of matter unite in certain definite proportions. Mr. Gurney lays it down as a law, that all the atoms of the same elementary body are mutually repellent, and the atoms of different elementary bodies are mutually attractive; he then states, that in compounds where the atoms of the different elementary substances are combined in the proportion of one and one, the form must be a cube; and he says, in fact, bodies chemically so combined, have this figure; that bodies in which the spherical elementary atoms are combined in the proportion of two to one, must necessarily have a figure with angles of 60° and 120°; and he affirms that bodies chemically so bined crystallize in this form. It is not in our power, particularly without his elucidating diagram, to fellow Mr. Gurney through all his illustrations, which are, however, very few; it is sufficient for us to state, that he has endeavoured to simplify the theory of crystallization, by showing how all the various crystals may, and, admitting the doctrine of chemical proportion, must assume the forms in which we meet with them, on the supposition of all the atoms or molecules of all the elementary bodies having the form of a perfect sphere. To us, who conceive the whole doctrine of atoms to be a mere vision of some philosophic brain, which, disdaining the common indulgencies of imagination, dreaming of houris and nectared fountains, and marble palaces, and golden statues, and ever-blooming gardens, indulges in the more lordly and creative work of framing out a universe anew, all this discussion about the primary form of atoms is little better than trifling amusement; and we might pass by Mr. Gurney's pretended discovery, as something like an idle dream; but the Reviewer, it must be remembered, is a stickler for the

doctrine of atoms, and, labouring even in this very Number of his Journal to recommend an opposite theory of crystallization to the notice of his readers, it was his business to show the incompleteness or the fallacy of Mr. Gurney's theory. He has not done this, and he has vacated the chair of rational criticism to indulge in low sneers and unmeaning notes of admiration and italics. This is utterly unworthy of a Journal edited at the Royal Institution. The Reviewer should have pointed out Mr. Gurney's errors, and warned the younger part of the scientific world from wasting their time and money in similar pursuits. That there are in Mr. Gurney's book several strange forms of expression, some visionary doctrines, and some very farfetched assumptions, is quite plain; but being combined with many acute observations, and with an inventive disposition on the part of Mr. Gurney, we must say that the attempt to sneer him down looks something like an effort on the part of the Royal Institution to stifle talents which have not grown into notice under their protection.

Mr. Gurney's other charge is, That the Reviewer has taken garbled extracts from his work. Let us see, then, if this accusation be true. The Reviewer says, p. 302, "We are told, in p. 46, that the crystals of alum EXACTLY RESEMBLE those of natural quartz." He quotes this paragraph to show Mr. Gurney was ignorant of the difference between the crystals of alum and those of quartz. In his Letter, Mr. Gurney explains, that the passage was meant to convey an idea that crystals artificially produced were deposited in a manner similar to that employed by nature. Here is the passage, and we ask the candid reader which sense it conveys. "In a short time the crystals of alum will be found to have DEPOSITED themselves about it, (a matrix,) in perfect IMITATION of natural quartz." The Reviewer, therefore, not only misquotes the words, but imputes a meaning to the passage which it does not convey. At page 306, the

Reviewer quotes as follows:-" Nitrogen, I suspect, is a peculiar compound, formed by the organs of the animal body, and not a simple element, as is generally supposed." -here he stops: Mr. Gurney adds, "when it is submitted to galvanic influence it neither goes to one pole or (nor) to the other, but holds almost a neutral situation between the two." The Reviewer makes this quotation, to sneer at Mr. Gurney; and certainly a mere supposition, without assigning any reason for it, that nitrogen is a compound substance, looks very ridiculous. But it is somewhat remarkable, that the same Number of the Quarterly Journal, and perhaps the same Reviewer, in an article on Dr. Henry's Chemistry, lays down the "the electrical relations of the elementary and undecompounded bodies," as the principles on which to found chemical classification; and the subsequent part of the paragraph should therefore, according to his own doctrine, justify the first part, which he endeavours, quoting it by itself, to render extremely ridiculous. In the same page, the Reviever, by omitting the word "seems," converts a passage, in which Mr. Gurney is speaking of phosphorus from a conjecture, to an absolute assertion. These instances are, we think, sufficient to justify Mr. Gurney's second accusation. The Reviewer has misquoted his book, and made garbled extracts. In fact, with the exception of a well-known bantering Magazine, we never remember to have witnessed, in any Journal possessing the least character, above all in a scientific Journal, so flagrant a violation of the just rules of criticism. We are not insensible to the gross defects of Mr. Gurney's book; and it must be stated, that he has laid himself open to much severe criticism, by a hasty publication. No man has a right to expect that his unpruned conjectures should be received as established facts; and till Mr. Gurney had found an opportunity of illustrating and confirming his theories, he should have