August 2, 1895.] 



SCIENCE. 



139 



Lard or tallow will assume the appearance 

 of a soft grease. 



The part of the work devoted to the 

 Quantitative Analysis is excellently written, 

 disclosing at once that the author is thor- 

 oughly familiar with the work. The latest 

 researches are carefully quoted and criti- 

 cised, the criticisms being usually strength- 

 ened by results obtained in his own labora- 

 tory. We refer the reader especially to 

 Twitchell's method for the determination 

 of Eesin Acids. On p. 196 he says : "Of 

 all the methods proposed hitherto for the 

 estimation of resin acids in mixture with 

 fatty acids, that recommended by Twitchell 

 yields the best results, and should therefore 

 be used to the exclusion of the methods de- 

 scribed before. The results, however, must 

 not be considered as absolutelj^ correct; 

 they are only approximate, as Lewkowitsch 

 has shown bj' an exhaustive examination 

 of both the volumetric and gravemetric 

 processes." The author then gives a series 

 of tables giving the results of this work. 

 Dr. Lewkowitscli's assumption that the 

 reason for the results by this process, being 

 only approximate, is due to the action of 

 hydrochloric acid upon the resin, has since 

 the publication of this work been shown to 

 be wrong. Evans and Beach in a recent 

 publication have shown that the low results 

 obtained by the gravemetric process is due 

 to a large percentage of unsaponifiable mat- 

 ter in the resin. They found as high as 9 per 

 cent, of unsaponifiable matter in one resin. 



The Chapters IX., X., XI. and XII. are 

 almost entirely rewritten and contain much 

 original work. The sulphur chloride test 

 for drying oils offers many interesting points 

 of inquiry. In the table given on p. 228 

 we find that tallow and lard do not thicken 

 with Sg CI2, and that the resulting product 

 is entirely soluble in carbon bisulphide, 

 whereas on p. 229 we find in another table 

 that tallow oil and lard oil (products ob- 

 tained by pressure from tallow and lard) 



solidify with S^ CI2 after 12 and 10 minutes 

 respectively and form products not com- 

 pletely soluble in carbon bisulphide. In 

 summing up the results of the various in- 

 vestigations on ' Color Reactions,' Dr. Lew- 

 kowitsch said that the results on all color 

 reactions should be taken with the greatest 

 caution and mention should be made that 

 the test for cotton seed oil with nitric acid 

 which the author so forcibly recommends 

 be included. The descriptions of the va- 

 rious oils, fats and waxes are very com- 

 plete. The part given to cotton seed oil is 

 especially so. In this one description we 

 find twenty-three different publications re- 

 ferred to, including articles from American, 

 English, German, French and Italian jour- 

 nals. 



We are very sorry to find Dr. Lewko- 

 witsch follows the footsteps of so many 

 European chemists, decrying everything 

 foreign. We should be pleased to know his 

 authority for the following: (p. 460) 'in 

 America adulteration has become an openly 

 acknowledged practice,' etc. It simply 

 points out to the American reader the cus- 

 tomary ignorance of foreigners regarding 

 our laws on the subject of adulteration. 

 In Chapter XII., devoted to Technical and 

 Commerical Analysis, lard and lard sub- 

 stitutes are dismissed with two and one- 

 half lines. It is upon this very subject 

 that a well directed system of investiga- 

 tions is necessary, and to judge by the 

 numerous cases of supposed adulterations 

 at all times before the English courts, Dr. 

 Lewkowitsch's works would be considered 

 the better for it, and must be considered 

 incomplete for the lack of it. 



Joseph P. Geabfield. 



Chicago, July 6, 1895. 



SCIENTIFIC JOURNALS. 

 AMERICAN JOURNAL OF SCIENCE. 



The August number of the American 

 Journal of Science opens with an article by 



