NA TURE 



23 



THURSDAY, MAY 8, 1879 



THE CHEMISTRY OF COMMON LIFE 

 The Chemistry of Conunon Life. By the late James 

 F. W. Johnston, M.A, F.R.S., Professor of Chemistry 

 in the University of Durham. A new edition, revised 

 and brought down to the present time. By Arthur 

 Herbert Church, M.A. (Blaclcwood and Sons, Edin- 

 burgh and London, 1879.) 



IT is now a great many years since the writer of the 

 present review first read the work which as edited by 

 Prof. Church he wishes to introduce to the readers of 

 Nature. He has not forgotten the keen interest and 

 pleasure which the book awakened in him as a boy, and 

 which were re-awakened when a few weeks ago the new 

 volume came into his hands. Though times have changed 

 since this book was published — now twenty-five years ago 

 —though we are now almost deluged with scientific 

 manuals and primers, intended to gratify the growing 

 taste for science, or rather, perhaps, to meet the needs of 

 our quasi-Chinese e.\amination systems, yet such books as 

 Johnston's " Chemistry of Common Life," or the equally 

 charming companion work, "The Physiology of Common 

 Life," by the late G. H. Lewes, have not been superseded. 

 Full of facts which it is often difficult to find elsewhere, 

 written in a style which will charm the most fastidious, 

 awakening at every step the reader' s desire to know more 

 of the subject which is treated of, these two works have 

 always appeared to us very models of popular scientific 

 writing. 



To edit such a work as " The Chemistry of Common 

 Life" so as to bring the book up to date without de- 

 parting from the author's plan or awakening unpleasant 

 comparisons, was by no means an easy task, and one 

 which could only be discharged adequately by an easy 

 writer, thoroughly conversant with chemistry, and not 

 unfamiliar with physiology ; the task has, we think, been 

 admirably performed by Mr. Church, and we recommend 

 the volume which he has edited as one eminently de- 

 serving of the study of the medical man and the student 

 of physiology. 



The first chapter'treats of " The Air we Breathe." In it 

 we find discussed the composition of the atmosphere, the 

 mode of preparation, and properties of its constituent 

 gases; the importance of the watery vapour of the air, 

 the formation of rain and dew, and their many uses ; the 

 accidental constituents of the air. The second chapter is 

 devoted to "The Water we Drink." Here we find discussed 

 the properties of hydrogen, the differences between a 

 chemical compound and a mechanical mixture, the powers 

 of water as a solvent, the quantities of mineral matter 

 in some river, lake, spring, and sea waters ; the causes 

 of the hardness of waters, the organic impurities of 

 water, the solubility of gases in water, and the importance 

 of the presence of oxygen in water in relation to the life 

 of fishes, besides many other topics which cannot be 

 enumerated. 



As an example of the way in which interesting informa- 

 tion is brought together and ingenious suggestions ad- 

 vanced, which are sure to arouse an inquiring spirit in the 

 reader, we quote the following very characteristic discus- 

 VoL. XX. — No. 497 



sion of the influence exerted by certain vegetable matters 

 upon the organic matters of water, with an ingenious ex- 

 planation of the mystery of the waters of Marah : — 



"Well-waters sometimes contain vegetable substances 

 also of a peculiar kind, which render them unwholesome, 

 even over large tracts of country. In sundry districts the 

 decaying vegetable matters of the surface soil are observed 

 to sink down and form an ochreous/(j:«, or thin yellow layer, 

 in the sub- soil, which is impervious to water, and through 

 which, therefore, the rains cannot pass. Being arrested 

 by this pan, the rain-water, while it rests upon it, dissolves 

 a certain portion of the vegetable matter, and when col- 

 lected into wells, is often dark-coloured, marshy in taste 

 and smell, and unwholesome to drink. When boiled, the 

 organic matter coagulates, and when the water cools, 

 separates in blocks, leaving the water wholesome and 

 nearly free from taste or smell. The same purification 

 takes place when the water is filtered through charcoal, 

 or when chips of oak wood are put into it. These 

 properties of being coagulated by boiling, and by the 

 tannin of oak wood, show that the organic matter con- 

 tained in the water is of an albuminous character, or 

 resembles white of egg. As it coagulates, it not only 

 falls itself, but it carries other impurities along with it, and 

 thus purifies the water — in the same way as the white of 

 egg clarifies wines and other liquors to which it is added. 



"Such is the character of the waters in common use in 

 the Landes of the Gironde around Bordeaux,' and in many 

 other sandy districts. The waters of rivers and of marshy 

 and swampy places often contain a similar coagulable 

 substance. Hence the waters of the Seine at Paris are 

 clarified by introducing a morsel of alum, and the river 

 and marshy waters of India by the use of the nuts of the 

 Strychnos potatorum of which travellers often carry a 

 supply. One of these nuts, rubbed to powder on the side 

 of the earthen vessel into which the water is to be 

 poured, soon causes the impurities to subside. In Egypt 

 the muddy water of the Nile is clarified by rubbing 

 bitter almonds on the sides of the water-vessel in the 

 same way. 



" In these instances the clarification results from the 

 iron compounds or the albuminous matter being coagii- 

 lated by what is added to the water, and in coagulating, 

 it embraces the other impurities of the water, and carries 

 them down along with it. Salt, and many saline matters, 

 have likewise the power of clearing many kinds of thick 

 and muddy water. So long as the water contains but 

 little dissolved matter, all its particles of mud remain a 

 long time suspended. But the addition of almost any 

 soluble salt, even in small proportion, will, as it were, 

 curdle the impurities, causing them to collect together and 

 to settle. 



" These cases, and especially that of the sandy Landes 

 of Bordeaux, and elsewhere, throw an interesting light 

 upon the history of the waters of Marah, as given in the 

 fifteenth chapter of Exodus — 



" ' So Moses brought Israel from the Red Sea, and they 

 went out into the wilderness of Shur ; and they went 

 three days in the wilderness, and found no water. And 

 when they came to Marah, they could not drink of the 

 waters of Marah, for they were bitter: therefore the name 

 of it was called Marah. And the people murmured 

 against Moses, saying, What shall we drink ? And he 

 cried unto the Lord, and the Lord showed him a tree, 

 which when he had cast into the waters, the waters were 

 made sweet.' "^ 



The chapter on Water is followed by others which treat 

 of "The Soil we Cultivate and the Plants we Rear," of 

 " The Bread we Eat ' ' and " The Beef we Cook.' ' Under 

 the heading of " The Beverages we Infuse " we find sepa- 

 rate chapters allotted to "The Teas," "The Coffees," "The 



• Vm-ri— Annates de Chim. et_dt Pilots., Septembre, 1853, p. 84,. 

 ' Exodus, XV, 22-25, 



