628 
NATURE 
[FEBRUARY 5, I914 
TECHNICAL CHEMISTRY. 
(1) The Fermentation of Cacao. Edited by H. H. 
Smith. With a foreword by Sir George Watt, 
C.I.E. Pp. lv+318. (London: John Bale, 
Sons, and Danielsson, Ltd., n.d.) Price 10s. 
net. 
(2) Chemistry and its Relations to Daily Life. By 
Prof. L. Kahlenberg and Prof. E. B. Hart. 
Pp. vii+393. (New York: The Macmillan 
Company; London: Macmillan and Co., Ltd., 
1913.) Price 5s. 6d. net, 
(3) Industrial Poisoning from Fumes, Gases, and 
Poisons of Manufacturing Processes. By Dr. 
J. Rambousek. Translated and edited by Dr. 
T. M. Legge. Pp. xiv+360. (London: Edward 
Arnold, 1913.) Price 12s. 6d. net. 
(4) The Application of Physico-Chemical Theory 
to Technical Processes and Manufacturing 
Methods. By Prof. R. Kremann. Translated 
from the German by H. E. Potts, and edited 
by Dr. A. Mond. Pp. xv+212. (London: 
Constable and Co., Ltd., 1913.) Price 8s. 6d. 
net. 
(1) HIS is a collection of essays published 
during the last few years in Germany, 
Holland, the United States, and this country, 
discussing the methods and effects of fermentation 
as applied to the preparation of cacao (“cocoa”). 
Raw cacao beans, on being removed from the 
pods and placed in covered heaps, undergo alco- 
holic and acetic fermentation of the adherent 
pulp. This loosens the testa of the beans, and 
improves the quality of the kernel by reducing 
the amount of bitter astringent substances, de- 
veloping the aroma, and producing the desired 
chocolate colour. As to how precisely the im- 
provement is effected there is difference of 
opinion. Oxidation, either direct or by means of 
an oxidase; the action of acetic acid, or of heat, 
or of glucoside-splitting enzymes, are some of the 
explanations put forward. 
Two important suggestions for improving the 
industry are made: one is that instead of trusting 
to chance to bring the right kinds of yeast, the 
planter should employ suitable cultures for start- 
ing and prolonging the fermentation. A definite 
culture of yeast would ensure a more uniform 
product. The second suggestion is that the 
“juice”? from the fermentation, large quantities 
of which are now run to waste, might be manu- 
factured into vinegar, which should become a 
considerable asset to the planter. 
(2) Theory has been kept down to the minimum 
in this work, which is intended for students of 
agriculture and home economics in (American) 
secondary schools. ~The authors take common 
NO. 2310, VOL. 92| 
substances for their material—water, air, vinegar, 
soda, coal, soap, sugar, clay, wool, bread, milk, 
and so on. By discussing and experimenting upon 
these the student is led to a knowledge of some of - 
the fundamental facts of chemistry. The descrip- 
tions are simple and interesting; the instruction 
is sound so far as it goes; and the more important 
points are emphasised by using different kinds of 
type in the letterpress. A good deal of life is 
infused into what many students would regard as 
the dry bones of chemistry, and many illustrations 
are provided which further serve to brighten the 
pages. Students who are not making chemistry 
their primary study, but desire to have some 
knowledge of the chemical properties of common 
articles, will find the book full of trustworthy 
information. : 
(3) Dr. Rambousek, a medical man and a 
chemist, is also professor of factory hygiene 
and chief State health officer at Prague. He may 
therefore be regarded as specially qualified to 
compile a work dealing with the occurrence of 
poisoning in industrial occupations. The number — 
of such occupations attended with risk is perhaps | 
in general scarcely realised. Thus besides lead and 
phosphorus poisoning, cases occur in connection 
with the larger chemical industries (sulphuric acid, 
bleaching powder, hydrochloric and nitric acids), 
and with the use of phosgene gas, chloro- and 
nitro-benzene, methyl bromide, carbon disulphide, 
aniline, petroleum products; brass, chromates, 
ferro-silicon, mercury, and nickel carbonyl. The 
author gives an outline of the dangerous pro- 
cesses, then describes symptoms and treatment, 
and finally gives an account of the preventive 
measures hitherto adonted or suggested. The 
field is so wide that exhaustive discussion within — 
the limits of one small volume is impracticable; 
but the large number of references supplied will 
help to remedy this defect. 
(4) This work, the English editor explains, is 
one of a series of monographs on technical chemi- 
cal methods of manufacture, written by experts 
and published first in Germany, where they have 
had an encouraging reception. 
The book contains the substance of lectures 
delivered by Prof. Kremann, whose experience 
has taught him that the beginner shows most 
interest in those problems of physical chemistry 
which have a bearing upon technical questions. 
Starting with the fundamental laws of the 
mechanical theory of heat, the law of mass action 
is deduced, and the maximum work of a chemical 
process discussed, the results being then applied 
to a consideration of the theory of gas engines 
and of gaseous and solid explosives. The pheno- 
mena of catalysis and pseudo-catalysis are next 
