Feb, 2 1, 1878] 



NATURE 



319 



2. That the admixture of the vapour of carbon bisulphide 

 does not sensibly lower the igniting point of coal-gas, 

 although alone, or mixed with hydrogen or carbonic 

 oxide, this vapour inflames at 400'' F. 3. The Davy 

 lamp, which is a protection in explosive mixtures of air 

 and firedamp, is not safe in similar mixtures of air and 

 coal-gas. 



The third paper in the section discusses the possibility 

 of making metallic magnesium available as a source of 

 artificial light : and the last paper, relating to the use of 

 illuminating materials, describes the construction of a 

 gas-burner, in which the waste heat of the flame is made 

 to raise the temperature of both air and gas to 500° or 

 600° F. before combustion, and thus to increase the 

 luminosity of the flame. 



The author's group of papers on water examination 

 and purification, and on the treatment of sewage and 

 other refuse, occupies nearly 300 pages of the volume 

 before us. The value of Dr. Frankland's investigations 

 in sanitary chemistry has been variously estimated, and 

 a glance over the pages before us recalls the wordy war- 

 fare that has been waged between the upholders of Dr 

 Frankland's system of water analysis and of the conclu- 

 sions founded upon the data afforded by it, and those that 

 put their trust in the method devised by Messrs. Wank- 

 lyn. Chapman, and Smith. We anticipate that the re- 

 publication of Dr. Frankland's papers will impart fresh 

 vitality to a controversy that seemed, happily, to be on 

 the wane. If, however, a renewal of the controversy is 

 likely to lead to re-investigation and substantial improve- 

 ment in the existing methods of water analysis, we shall 

 not regret the re-opening of the subject. 



The chief aim of all modern methods of water analysis 

 is the detection and estimation of organic (especially 

 sewage) contamination. Dr. Frankland seeks to attain 

 the end in view by direct estimation of the " organic " 

 carbon and nitrogen in the water, while Messrs. Wanklyn, 

 Chapman, and Smith attempt to estimate the nitrogenous 

 organic matter in water by breaking up the organic bodies 

 and separating their nitrogen in the form of ammonia — 

 " albumenoid ammonia." A rather extended experience in 

 the use of both methods has led us to conclude that Dr. 

 Frankland's plan, though nearly perfect in point of 

 theory, is not as satisfactory in practice ; while the rival 

 method rests on a bad foundation, but is not likely to 

 lead to error in excess. We may state this much without 

 trenching too far upon technical ground, but we do so in 

 order to justify the desire above expressed for a re-inves- 

 tigation of the subject, conducted with a view to render the 

 theory and iiractice of water analysis equally satisfactory. 



It is scarcely necessary to mention that we find in this 

 section Dr. Frankland's valuable papers on the develop- 

 ment of fungi in potable water ; on the deterioration of 

 potable water during its passage through cast iron mains 

 and leaden service pipes ; on the methods of softening 

 " hard " water, and on the comparative purity of water 

 from various geological strata, and from different sources 

 such as mountain streams and lakes, rivers, shallow wells, 

 artesian wells, and springs. In addition, experimental 

 data are given showing the extent to which polluted water 

 can be purified by various means and rendered fit for 

 domestic purposes. These papers, together with those on 

 sewage treatment, are of especial value to sanitary engi- 



neers, and will no doubt be more freely consulted in their 

 present well-connected form than when scattered through 

 other publications. 



In Section III. Dr. Frankland returns to gases and 

 vapours — evidently favourite subjects of study with him 

 since the date of his discovery of the alcohol radicles — 

 but now from the physical side. The first investigations 

 detailed in the section arc those upon the effect of pres- 

 sure on combustion, which led him to conclude that 

 the luminosity of ordinary flames] is chiefly due to the 

 presence of incandescent vapours or gases of high 

 density, rather than to solid particles. The author's 

 experiments on the combustion of hydrogen and carbonic 

 oxide under great pressure proved that incandescent gases 

 and vapours emit light in proportion to their density, 

 and that a continuous spectrum can be afforded by 

 dense gas as well as by solid or liquid matter. 

 These observations led to the suspicion that the sun's 

 photosphere consists of gases or vapours only, and ulti- 

 mately to the commencement of a new line of research 

 in conjunction with Mr. J. Norman Lockyer, who was 

 then engaged on his researches on the physical constitu- 

 tion of the sun. Dr. Frankland was soon obliged to 

 relinquish the investigation, owing to pressure of other 

 work ; but in Mr. Lockyer's hands it has since afforded 

 results of the highest interest and value. 



Excluding a chapter on climate, and some miscellaneous 

 observations, the last research detailed in the volume 

 before us is a highly important one on the source of mus- 

 cular power. This inquiry is really complementary to the 

 well-known investigation of Profs. Fick and Wislicenus 

 on the same subject, for Dr. Frankland ascertained by 

 direct calorimetrical determinations the potential energy 

 locked up in muscle and in its chief products of oxidation 

 — urea, uric acid, and hippuric acid — and proved that the 

 store available was much less than would suffice to 

 account for the work done by Fick and Wislicenus in 

 the ascent of the Faulhorn. Frankland's experiments 

 conclusively proved that the muscular force expended by 

 the two professors in the ascent of the mountain must 

 have been chiefly derived from the oxidation of non- 

 nitrogenous matters, since it could not have been pro- 

 duced by the oxidation of muscle or other nitrogenous 

 constituents of their bodies. This investigation is one 

 of the most valuable in the section, and will be re-read 

 with special interest in connection with the Rev. Prof. 

 Haughton's latest researches. 



We cannot conclude this short sketch of Dr. Frankland's 

 admirable researches without giving expression to the 

 hope we entertain that the well-arranged volume before us 

 may prove to be but an instalment of the life-vfork of its 

 distinguished author. J. Emerson Reynolds 



FLORA OF TROPICAL AFRICA 



Flora of Tropical Africa. By Daniel Oliver, F.R.S., 

 F.L.S., Keeper of the Herbarium and Library in the 

 Royal Gardens, Kew, and Professor of Botany in Uni- 

 versity College, London. Assisted by other botanists. 

 Vol. iii. Umbelliferte to Ebenacea;. Published under the 

 Authority of the First Commissioner of Her Majesty's 

 Works. (London : L. Reeve and Co., 1877.) 



THE third volume of Oliver's "Flora of Tropical 

 Africa" includes fourteen natural orders, mostly 

 belonging to the sub class Gamopetalte of the Dicotyle- 



