September 7, 1906.] 



SCIENCE. 



307 



factors constitute the retainers, servants and 

 domestic animals of the evolutionary house- 

 hold, but this does not give them places in the 

 genealogy of evolutionary causes. 



Dr. Ortmann is annoyed by incidental 

 changes in familiar lines and stage directions, 

 which he does not hesitate to charge to care- 

 lessness and ignorance, forgetting, for the 

 time, that the whole play is being recast, and 

 that the merits of the new rendering are to 

 be judged by its conformity with the facts of 

 nature, rather than by reference to the tradi- 

 tions of evolutionary literature. 



O. F. Cook. 



Washington, 

 July 18, 1906. 



TEMPERATURE CORRECTIONS OP SUGAR 

 POLARIZATION. 



To THE Editor op Science: There has come 

 to me a belated copy of Science (April 20) 

 containing Dr. Wiechmann's review of my 

 work on the polariscope, in which he discusses 

 my treatment of the subject of temperature 

 corrections of sugar polarizations. As Dr. 

 Wiechmann seems to have quite misunder- 

 stood what I have stated concerning tempera- 

 ture corrections, in view of the great impor- 

 tance of the subject I have ventured to bring 

 it again before your readers. Dr. Wiechmann 

 takes a quotation from my book (p. 44) as to 

 the fact that the values of temperature influ- 

 ence are well established [by Andrews, Wiley 

 and Schonrock for instance] as a statement 

 endorsing the use of temperature corrections 

 in raw sugar polarizations. He quite over- 

 looks the statement (on the same page, I think ; 

 I have no copy at hand) that such corrections 

 can be qidte fallacious if proper conditions are 

 not observed; and yet further (p. 97?), under 

 ' Errors of Commercial Polarizations,' where 

 I say, that owing to other inherent errors of 

 raw sugar polarizations it is doubtful whether 

 application of such corrections brings any 

 nearer approach to the true saccharimetric 

 value; and hence, such corrections are ques- 

 tionable in raw products at least. 



The present status of the case, as I under- 

 stand it, is this : 



It is well established that temperature 



change exerts an influence on sugar polariza- 

 tions made according to standard method. 



The quantitative value of such influence, 

 when pure sugar is polarized, is known within 

 narrow limits of error. 



Owing to obscure compensatory errors, not 

 yet possible of measurement and inherent in 

 raw sugar polarizations, the correction of tem- 

 perature influence is inadvisable as generally 

 leading to an exaggerated sugar value. Fur- 

 ther, application of temperature correction 

 values gives quite fallacious results if the 

 same constant temperature of solutions and 

 apparatus is not maintained. 



As the total errors or raw-sugar polariza- 

 tions apparently come nearest to balance at 

 20° C. this temperature has been adopted as a 

 rigid standard by the International Sugar 

 Commission. 



The fact that the International Commission 

 has adopted a rigid temperature standard 

 shows that the influence of temperature is 

 recognized. It follows that polarizations made 

 at temperatures other than 20°, as necessarily 

 here in the tropics where the afternoon tem- 

 perature is now from 28 to 30°, that some 

 correction should be made for temperature 

 influence, not to the standard, of 17.5°, but 

 to 20°. The well-known case cited by Dr. 

 Wiechmann simply emphasizes that 'tempera- 

 ture corrections ' may be applied with quite 

 fallacious results, without in any way casting 

 doubt on the ' alleged ' influence of tempera- 

 ture on the specific rotation of sucrose which 

 obviously is but a small part of the influence 

 of temperature on sugar polarizations. 



Here might be raised the interesting and 

 subtle question whether the sugar values of 

 the saccharimeter standardized at 20° are 

 identical with those of the instrument stand- 

 ardized at 17.5° when raw sugars are polar- 

 ized. 



In the whole discussion, what are facts of 

 experiments in temperature influence on pure 

 sugar polarizations must be carefully differ- 

 entiated from what is the most consistent and 

 fairest way to estiraate the sugar value of a 

 commercial product, by the indications of a 

 method which at its best is subject to errors as 



