388 



NATURE 



S^Feb. 27, 1890 



work has special reference to the applications of 

 chemistry to the arts and manufactures, it deals but 

 sparingly with the purely scientific aspects of the science, 

 unless these have some direct and immediate bearing on 

 the business of the technologist. How direct and how 

 immediate such a bearing is at the present day, and how 

 difficult, not to say impossible, it is to separate theory 

 front practice, may be judged of by turning over the 

 pages of this most useful volume. 



Take, for example, the article on the azines, written by 

 the most competent authority on that subject, Dr. Otto 

 Witt, of Berlin. The untrained technologist will be com- 

 pletely at sea with the honeycomb of benzene rings with 

 which he clearly explains the constitution of such well- 

 known compounds as the safranenes, the splendid yellow 

 dyes so ably investigated by Dr. Witt himself, whereas 

 the manufacturer who has the theory of the subject at 

 command is complete master of the situation. Or, again, 

 let us turn to the next article, on the azo-colouring matters, 

 communicated by another equally trustworthy authority. 

 Prof. Meldola, covering 28 thickly-printed pages, in which 

 the same necessary connection is seen. And no other 

 example, perhaps, indicates more forcibly the enormous 

 advance which applied chemistry has made in the last ten 

 years, and its entire dependence upon abstract research. 

 In proof of this, it needs only to be pointed out that the 

 article concludes with a list of no less than 95 distinct 

 patents on this one group of colouring matters, from 

 March 12, 1878, to June 30, 1888, all of which are the 

 result of original, chiefly German, research. 



An examination of other important articles written by 

 specially-qualified contributors indicates that each sub- 

 ject is brought up to the level of the present state of our 

 knowledge. Let us look for a moment at the article on 

 ammonia, contributed by Prof. Lunge, of Zurich. Here 

 we find detailed reference to the newest forms of appa- 

 ratus for the manufacture of ammonium salts, illustrated 

 by excellent woodcuts of the Feldmann-still. Again, 

 turning to the article on chlorine, we have to note the 

 same completeness and technical grasp of the questions 

 discussed. Thus, on p. 526, we find the method patented 

 so long ago as 1866 by Mr. Brock, of Widnes, and now 

 for the first time coming into general use, which has for 

 its object the treatment of the exit gases from the 

 bleaching-powder chambers by means of a dry lime- 

 sprinkler, this not only removing a serious nuisance in 

 the manufacture, but also recovering chlorine otherwise 

 wasted. 



Prof. Hummel, of Leeds, contributes an excellent 

 article on bleaching; and here again we see that the 

 newest processes are fully described, e.g. on p. 323 the 

 Mather-Thompson bleaching process is fully noticed, and 

 the electrical bleaching process of Hermite likewise re- 

 ferred to. As regards this latter, the conclusion arrived 

 at is that now generally admitted by practical authori- 

 ties, viz. that electrolytic bleaching cannot reasonably be 

 expected to replace bleaching-powder at a price of ^7 

 per ton. 



One of the most valuable articles in the book is written 

 by Mr. John Heron on brewing, in which he not only 

 describes the most modern forms of brewing plant and 

 processes, but gives a clear statement of the important re- 

 searches of Pasteur and Hansen on the alcoholic ferments. 



As we all know, it was Pasteur who first directed attention 

 to those other forms of Saccharomyces known as "wild" 

 yeasts in fermenting yeasts and beer ; but it is not so- 

 commonly understood that it was Hansen who taught us 

 how to introduce into the liquid a seed yeast really free 

 from " wild" forms. Since 1883 carefully selected types 

 of yeast from pure cultures, according to Hansen's re- 

 searches, have been introduced into Denmark, Norway, 

 and Bavaria, with the most satisfactory results, whilst in 

 England nothing of the kind has yet been done, although, 

 at Burton several experiments have been made in this 

 direction. Sufficient has already been done to show that 

 several varieties of Sacchai'omyces cerevisicB can be 

 separated, which, however, do not differ morphologically, 

 but may be distinguished from each other, inasmuch as 

 they give entirely different results, both as to flavour 

 brightness, attenuation of the beer, and to the mode of 

 separation of the yeast. The proportion of these different 

 varieties in various breweries seems to remain constants 

 and to give the peculiar flavour and appearance which 

 the various fermented liquors possess. 



Another article is that by Prof. Noel Hartley on 

 cements, a subject which though of great importance is 

 not usually considered of great chemical interest, but it 

 has been made so by th e writer. He points out the facty 

 certainly not known to the majority of chemists, that we 

 owe to Lavoisier the first explanation of the phenomena 

 of the baking and hardening of plaster of Paris. At 

 so early an age as 21, he published a short note in 

 the Comptes rcndus of February 17, 1765, in which he 

 showed that water is removed from the gypsum in two 

 stages, that the first three-quarters of the combined 

 water must be removed in order that the plaster shall 

 afterwards set, but that if the whole of the combined 

 water be removed, the gypsum becomes overburnt and 

 loses its value as plaster. 



It is probable that this volume will have even a larger 

 \ sale than that of the corresponding " Dictionary of Pure 

 i Chemistry," and, as with that important work, so with 

 ! this, the public may well be congratulated on possessing 

 j such a valuable book of reference so creditable to all 

 concerned in its production. H. E. RoscOE. 



OATES'S ORNITHOLOGY OF INDIA. 



The Fauna of British India, including Ceylon and 



Bitrma. Published under the authority of the Secretary 



of State for India in Council. Edited by W. T. 



Blanford. Birds. Vol. I. By Eugene W. Oates. 



Pp. i. — XX., I — 556. (London : Taylor and Francis, 



1889.) 

 The Nests and Eggs of Indian Birds. By Allan O. 



Hume, C.B. Second Edition. Edited by E. W. Oates. 



Vol. I. Pp. i. — xii., I — 397, (London : R. H. Porter, 



1889.) 



THE two volumes on the birds of India, which Mr. 

 Oates has recently published, will supply a much 

 needed want. The period of twenty-six years which has 

 elapsed since the publication of Jerdon's *' Birds of India" 

 has been prolific in ornithological work, to such an 

 extent that a new adjustment of the scattered details 

 which had accumulated since that time had become an 



