May j;, 1894] 



NA TURE 



51 



of the learned. Possibly the alchemists really attached 

 some definite meaning to the fantastical terms they used, 

 which meanings are now lost to us. 



When the use of the accurate balance was introduced 

 into natural science, it revolutionised the methods of 

 investigation : it now became possible to trace the 

 changes which occur during the interaction of bodies 

 in a way quite different from that employed in earlier 

 times. Thus the alchemist observed only the changes 

 of properties of the substances with which he experi- 

 mented ; the chemist investigates, in addition, the 

 changes of mass which occur when alterations of matter 

 are produced. 



It must not be supposed that the early workers were 

 ignorant of the increase of weight which occurs during 

 the calcination, or, as we now call it, the oxidation of 

 metals, but they gave very fanciful explanations of the 

 fact ; thus George Wilson, in his " Compleat Course of 

 Chymistry,' printed in 1721 (how many students at the 

 present time would rejoice in a complete course of 

 chemistry in 383 pages ! ) says, when writing of the calci- 

 nation of lead, " It gains in weight by calcination, 

 because a greater quantity of igneous particles insinuate 

 themselves into the lead, than the sulphurous ones the 

 fire drives out, for in calcination, the acid of the fire, 

 joins itself to the alkali of the lead, and having driven 

 away its combustible sulphur, makes a new and 

 incombustible body." 



Mr. Pattison Muir gives some illustrations of the use 

 of the balance, but one of these seems not quite a happy 

 example. He states that when water was evaporated in 

 an open dish and a residue was left, the alchemist 

 "pointed to the earthy matter in the dish as proof of the 

 tran'sformation of water into earth." He afterwards says 

 that a weighed quantity of water was distilled, the dis- 

 tillate was weighed and was found to be less than the 

 original water ; "but the sum of the weights of the con- 

 densed water and the earthy matter was equal to the 

 weight of the water before boiling," showing that the 

 residue was dissolved in the water used. It is not stated 

 by whom this experiment was made, but it is inferred 

 that it was performed in the early days of quantitative 

 work. As spring water rarely contains more than one- 

 tenth per cent, of dissolved matter, it would have been 

 interesting if the author had informed us what precau- 

 tions were taken to secure such a- result, which would be 

 difficult even with our modern appliances. 



By the use of the balance it was found that some sub- 

 stances differed from others, some being composed of 

 differei^ kinds of matter, and hence called compounds, 

 whilst otlwrs could not be thus separated, and were re- 

 garded as simple bodies or elements. When an element 

 is transformed into a compound, the latter almost invari- 

 ably possesses properties very different from those of the 

 element, and the element appears to have been destroyed ; 

 the alchemist thought that it was really destroyed, but 

 the chemist shows that it is only hidden, and can be 

 obtained from the compound in the same quantity that 

 was used to prepare the compound ; moreover, the weight 

 of the compound is invariably equal to the sum of the 

 weights of the elements composing it. 



As far as we know at present the elements are un- 

 changeable ; however complex the compounds which are 

 NO. I 28 1, VOL. 50] 



formed by their combination, the elements can always be 

 obtained from them with all their original properties. 

 Thus the formations of compounds from elements and 

 the decomposition of compounds into elements are 

 properly called the " changes in combinations of the 

 unchanging." The alchemical principles could not be 

 weighed or measured, so that it was not possible to ex- 

 plain the properties of bodies by the assertion— for it was 

 nothing more — that they contained more or less of these 

 principles. 



The author next tells us that the same elements in the 

 same proportions can form compounds with different 

 properties, and then passes on to the laws of multiple 

 proportions, showing how these are accounted for by the 

 theory of atoms. The periodic law is then explained, 

 and it is pointed out that the periodic properties of the 

 elements and of their compounds contrast very strongly 

 with the ideas of the alchemists with regard to the 

 principles that were supposed to account for the different 

 properties of substances. The striking difference between 

 alchemical and chemical reasoning is well illustrated by 

 the history 01 the theory of combustion, the escape of 

 the principle of fire, as held by the phlogistians to be the 

 cause of combustion, being contrasted with the combina- 

 tion of the burning substance with o.xygen, as discovered 

 by Lavoisier. 



The author appears to be rather hard on alchemy when 

 he says " the great business of alchemy was to prevent 

 men from coming into close contact with external 

 realities. Alchemy was a manufacturer of blinkers that 

 shut off the objects on either side, and so distorted the 

 vision." No doubt this was in some ways the result of 

 alchemy, but it can hardly be supposed that it was its 

 object. It is difficult to place ourselves, even in imagina- 

 tion, in the position of the alchemists, but we may 

 hope that they were struggling after truth to the best of 

 their powers, their failure being due more to their hold- 

 ing preconceived notions than to a desire to obscure 

 facts. 



Some may not agree with the author in classing 

 together alchemists, spiritualists, theosophists, and 

 theologians ; though, no doubt, all have erred in making 

 assertions with an insufficient knowledge of facts. So 

 also it seems not quite justifiable to restrict the term 

 science to the investigation of natural phenomena, for 

 surely the study of the moral and spiritual actions of 

 man are also worthy of the name of science. Some may 

 not accept spiritual truths, considering that they are 

 beyond their experience ; but it is hardly scientific to deny 

 their existence, any more than it was reasonable for the 

 inhabitants of Flatland to deny the existence of space 

 of three dimensions. 



I\lr. Pattison Muir's book will well repay perusal ; it 

 will appeal not only to the chemist, but also to the general 

 reader, who cannot fail to obtain much insight into the 

 ideas of the alchemist, and also into the accurate methods 

 of the modern chemist. HEKUliRT McLeod. 



OUR BOOK SHELF. 

 Principia Nova Aslronomiat. By Henry Pratt, M.D. 



(London: Williams and Norgate, 1S94.) 

 We confess to having read a great deal of this book, 

 and to have wasted a corresponding amount of time. 



