170 SCIENCE PROGRESS 



subject Mr. Stebbing is doing not only work of interest but of great economic 

 importance. 



The report gives the first good account of the coccid in all its stages and an 

 account of its life-history. Then follows a list of lac-yielding trees — acacias, 

 albizzias, atrocarpus, anona, etc., as well as cajanus, butea, ficus, and zizyphus — 

 from which commercial lacs are obtained, and the Schleichera trijuga, which 

 yields the finest lac of all and is the most important of all lac-bearing trees. 



Speaking of the injury done to the trees by the lac insect, Mr. Stebbing says : 

 " It is probably but rarely that the trees are ever killed by the insect." 



This valuable scale-insect is preyed upon by various enemies, such as the 

 larvae of Galleria and Eublemma, but we learn that very little is known about 

 them. 



Valuable chapters follow on its distribution, exploitation, and the necessary 

 steps to be taken to improve its cultivation and collection. The whole must prove 

 of the greatest service in stimulating and improving one of the many resources of 

 India. If the beautiful cochineal dyes are or have largely been superseded by 

 the fugitive and crude chemical colours, this insect product is more than holding 

 its own. 



Fred. V. Theobald. 



On Some Assam Sal (S/iorea robusta) Insect Pests. By E. P. Stebbing, F.L.S., 

 etc. Forest Bulletin No. 11 (1907). Price 2s. 6d. 



This is the first account of the insect enemies of this valuable Indian tree, which 

 is too frequently defoliated by the caterpillars of various moths, as Dasychira and 

 Lymantria. 



Amongst the various enemies dealt with is the Sal-borer {Hoplocerambyx 

 spinicornis, Newn.) ; Dasychira horsfteldi, Saund. ; Lymantia mathura, Moore ; 

 and new species of Spharotrypes, Thanasimus, and several new Scolytida. Life- 

 histories and preventive and remedial measures are given, which, with the 

 excellent plates, form a work of not only scientific but great practical value. 



Fred. V. Theobald. 



Text-books of Physical Chemistry : Thermochemistry. By Julius Thomsen, 

 Emeritus Professor of Chemistry in the University of Copenhagen. Trans- 

 lated by Katherine A. Burke. [Pp. xv. + 495.] (London: Longmans, 

 Green & Co., 1908 ; price 9^.) 



Except for a short account of experimental calorimetric methods taken from the 

 Thermoche7nisihe Untersuchungen, this volume is a translation of Prof. Thomsen's 

 more recent Danish work, Thermokemiske Resultater. In this latter book he has 

 summarised the results of his laborious thermochemical investigations, which are 

 presented here for the first time in a readily accessible form. To the extraordinary 

 energy and zeal of the investigator this valuable compendium of thermochemical 

 data bears eloquent testimony ; it is an instructive example of what may be 

 achieved by a single scientific worker who devotes his life to research on one 

 particular line. 



While welcoming another of these Text-books of Physical Chemistry, one may 

 at the same time express regret that it has not been possible to provide a volume 

 on Thermochemistry written especially for this series, and dealing with this 

 branch of the science from a detached point of view. An account, such as is 

 given in this book, of the researches of an investigator like Thomsen is bound to 



