272 



DISCOVERY 



splendours of the Sky. By Miss Isabel Lewis. (John 

 Murray, los. 6d.) 

 An illustrated book on popular astronomy written 

 originally for magazine readers. Very readable and quite 

 up-to-date. 



Philosophy and the Christian Religion. By Prof. 

 C. C. J. Webb. (Clarendon Press, is. 6d.) 

 A lecture on this subject by the new Oriel Professor of 

 the Interpretation of Holy Scripture, Oxford University. 



Rdalivity. The Special and the General Theory. By 

 Prof. A. Einstein. Translated by R. W. Lawson, 

 D.Sc. (Methuen, 5s.) 

 In this book, which is written for the average reader, 



VtoI. Einstein explains his famous theory. Clearly 



written and admirably translated. 



The Birth of Chemistry 



By H. D. Murray 



Exhibitioner of Christ Church, Oxford 



The science of chemistry may be said to have had its 

 birth in the seventeenth and eighteenth centuries. It 

 is, perhaps, preferable to speak rather of its evolution 

 during this period, since chemistry gradually grew out 

 of the old art of alchemy, which, up to the time of 

 Paracelsus, that is the middle of the sixteenth century, 

 had existed as an art chiefly directed to mean ends 

 and having a close connection with magical practices. 

 This process of evolution began when the old alchemy 

 became raised to a higher status by its alliance with 

 the profession of medicine. Not, however, until nearly 

 150 years later, when chemistry began to free itself 

 from the limitations imposed upon it by its application 

 to medicine, do we see in it any real growth as a science. 

 From that time up to the latter part of the eighteenth 

 century, when Lavoisier introduced the use of the 

 balance, and so gave to chemistry the form which it now 

 bears, it was dominated by the phlogistic theory. In 

 spite of this, however, the latter period was rich in 

 discoveries and fruitful hypotheses. 



In order to understand the w-orld of thought in 

 which the science of chemistry was born, it is necessary 

 to study first the legacy of the alchemists to that world. 

 Their knowledge, which was largely empirical, had 

 its origin in Egypt. The two great theories which 

 coloured all their views were the belief in the transmu- 

 tation of metals and in the existence of the philosopher's 

 stone. To the latter were ascribed many properties, 

 which varied from time to time, some of them — such 

 £is the prolongation of life — partaking of a magical 



nature. A full account of these properties, stated in 

 less extravagant and obscure terms than those used 

 by Paracelsus and others, is given by Andreas Libavius 

 in his Alchymia. 



The views of the alchemists as to the constitution 

 of matter were largely founded upon those of 

 the ancient philosophers. The latter recognised in the 

 world four distinct principles — solidity typified by 

 the earth, wetness by water, combustibility by fire, and 

 the gaseous state by the air. The alchemists, however, 

 directed their attention chiefly to the first three prin- 

 ciples or elements, using the word probably in a 

 different sense from that used to-day. This may have 

 been due to their very scanty knowledge of gases, 

 which were usually neglected in reactions, and were 

 only classified as combustible and non-combustible. 

 They were all known by the generic term of air. Basil 

 Valentine put forward the view that all substances 

 consist of three elements — sulphur, mercury, and salt — 

 in varying combinations, and the idea received con- 

 siderable support. Although general knowledge of 

 chemical reactions was small, metallurgy', extraction 

 from ores, and formation of alloys had been more 

 thoroughly studied, both from the utilitarian point 

 of view and as being the readiest point of attack in the 

 problem of the transmutation of metals. In this latter 

 connection, the properties of acids and their action 

 upon various substances were also better known ; in 

 aqua regia they thought to have found the long-sought 

 alkahest, or universal solvent. There is a tendency 

 nowadays to believe that the knowledge of the al- 

 chemists was greater than that formerly attributed 

 to them. Their WTitings are, however, so very vague 

 and so often fuU of mystical terms that it is easy, in 

 the light of our present knowledge, to read into some 

 sentence a meaning which, from other sources, we 

 find the writer never intended. 



Alchemy may be said to have received the first of 

 the blows which eventually killed it in the teachings of 

 Paracelsus. It is true that he was a firm believer in 

 the transmutation of metals, but we find such alchemis- 

 tic views occurring even up till the nineteenth century. 

 Dippel, who lived in Berlin early in the eighteenth 

 century, is known traditionally as the last of the 

 alchemists ; but the last great chemist to support 

 many of the alchemist c ideas in his teaching was 

 Boerhaave, who died in 1738. 



The period dating roughly from the middle of the 

 sixteenth century is known as that of the iatrochemists, 

 and is marked by the attempts made to fuse chemistry 

 and medicine. Paracelsus, and later de la Boe Sylvius 

 (1614-72) and Tachenius, Sylvius' pupil, were the 

 leaders in this attempt. Although we see little ad- 

 vance in actual knowledge during this period, yet 

 chemistry can be said to have continued its evolution, 



