Maech 1, 1907] 



SCIENCE 



343 



In the determination of sulphurous acid by 

 the official method, the sample is distilled with 

 dilute phosphoric acid in a current of carbon 

 dioxide, the distillate collected in standard 

 iodine solution, the excess of which is titrated 

 with sodium thiosulphate. 



The method more generally used consists in 

 collecting the sulphurous acid in iodine solu- 

 tion, boiling off the iodine and precipitating 

 the resulting sulphuric acid as barium sul- 

 phate. This method gives lower results than 

 the official method, indicating that substances 

 other than sulphurous acid distil over and 

 reduce the iodine. 



Samples of gelatin were analyzed by both 

 the above methods and by different chemists. 

 The results obtained varied considerably be- 

 tween the methods and between the chemists. 

 Furthermore, sulphurous acid was reported 

 where no sulphur in any form had been added 

 to the gelatin. This last is explained by a 

 consideration of some recent work on the de- 

 termination of sulphurous acid in meat where 

 a certain amount of sulphur is found to be 

 normally present. 



This work on gelatin makes it evident that 

 since most of the food standards are based on 

 the presence or absence of definite percentages 

 of certain elements or compounds, it is of vital 

 importance that chemists compare notes and 

 see what degree of concordance is practicable 

 with our present tentatively official methods 

 and agree upon some reasonable limit of toler- 

 ance to cover the differences due to personal 

 equation and imperfect analytical methods. 



The technical portion of the paper was sup- 

 plemented by remarks from Dr. Leo Baeke- 

 land. 



A Preliminary Communication, on the Tox- 

 icity of some Aniline Dyestuffs: Gustave 

 M. Meyer. 



Seven dyestuffs commonly used as food col- 

 orants were obtained from a dealer and in- 

 vestigated. The experiments were made on 

 dogs and included, besides observations of the 

 general influence of these substances, also 

 studies of their elimination. The amount of 

 dye used was increased daily until toxic symp- 

 toms were shown. The animals were finally 



chloroformed and subjected to a post-mortem 

 examination. With one exception, the only 

 outward symptoms induced by the feeding of 

 these dyestuffs were such as would be brought 

 about by the administrations of equally large 

 amounts of any of the ordinary saline purga- 

 tives. 



In a general way it may be said that, judg- 

 ing from the amounts given and the compara- 

 tively slight effects produced, these dyestuffs 

 can hardly be classed among virulent poisons. 

 What symptoms they would produce if admin- 

 istered daily in small doses during a very long 

 period to unhealthy animals is still unde- 

 termined. 



Studies of the influence of coal-tar colors 

 on peptic digestion in vitro indicated that 

 all dyestuffs almost completely inhibited pep- 

 tolysis when present in a concentration of 

 0.62 per cent, or more. Gudeman's statement 

 that synthetic dyes have a certain food value 

 was investigated by this method without ob- 

 taining confirmatory results. Direct conclu- 

 sions as to the effect of these substances on the 

 human body can not, however, be drawn from 

 experiments on digestion in vitro since certain 

 substances have opposite effects in the two 

 cases. 



Dr. Meyer's paper was ably discussed by 

 several experts on the subject who were pres- 

 ent. These included Messrs. Coblentz, Lieber 

 and Schweitzer. C. M. Joyce, 



Secretary 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



Tpie 627th meeting was held on January 19, 

 1907, President Hayford in the chair. The 

 evening was devoted to a paper by Dr. R. S. 

 Woodward upon ' The Theory and Application 

 of the Double Suspension Pendulum.' 



The 628th meeting was held on February 2, 

 1907. 



Professor ISTewcomb read a paper on the 

 ' Optical and Psychological Principles In- 

 volved in the Interpretation of the Markings 

 on the Discs of the Planets.' 



Two sets of principles were discussed: one 

 optical — including all the causes which affect 

 the formation of an image on the retina of 

 the eye, the other psychological — including all 



