384 EXPERIMENT STATION RECORD. 



The detection of arsenic by biological means, W. Haismann (Bei&r. Chem. 

 Physiol, a. Pathol., 5 [1904), No. 7-8, pp. 397, 398). — A summary of observations on 

 the detection of arsenic by means of Ailpasia diaphana, together with references to 

 the work of other investigators. 



A short method of estimating- glycogen quantitatively, E. I'ri.i <;i:k (Arch. 

 Physiol. {Pfluger], 103 {1904), No. 8-4, pp. 169, 170). The method described con- 

 sists in heating for l' hours 100 grn. of finely divided material in 100 cc. of HO per rent 

 boiled potassium hydroxid solution, cooling, ami diluting with 200 cc. sterilized 

 water ami 400 cc. of 96 per cent alcohol. After the suspended material has settled 

 the solution is filtered and the precipitate washed with a mixture of 15 per cent 

 potassium hydroxid solution ami 96 per cent alcohol 1 :L', and then with 00 per cent 

 alcohol. 



The precipitate (with the filter paper) is boiled in water and the solution neutral- 

 ized. If a large amount of protein is separated a second filtration and boiling with 

 water is necessary. Hydrochloric acid is added until the solution contains 2.2 per 

 cent, and inverted for :; hours. After cooling, neutralizing, and filtering the amount 

 of su«rar is estimated with a polariseope. The sugar value multiplied by the factor 

 0.927 gives the glycogen value. 



Analyses of rocks from the laboratory of the United States Geological 

 Survey, 1880 to 1903, F. W. Clarke (U.S. Geo!. Sun,,/ Bui. 228, pp. 375).— A 

 revised edition of Bulletin 168, including nearly 300 new analyses. "In this edition 

 the names are stated which the rocks would hear in the classification proposed in 

 1903 by Messrs. Cress, hidings, Pirsson, and Washington, and set forth by Doctor 

 Washington in Professional Paper No. 14. Mr. Clarke has also given a new compu- 

 tation of the average composition of rocks, closely agreeing with his former estimates, 

 but founded upon more extensive data." 



The measurement of ultramicroscopic particles with especial reference to 

 colloid gold solutions and gold glass, H. Siedentoph and R. Zsigmondy (Ber. 

 Devi. Phys. Gesell, 5 (1903), No. 11, j>p. 209-216, fig. 1).— The method of rendering 

 visible and measuring ultramicroscopic particles has been rioted from another publi- 

 cation (E.S.R v 16,p.l5), 



Estimating the hydrothermal equivalent of a Berthelot bomb calorimeter 

 in electrical units, W. Jaeger and H. von Steinwehr (Ber. Dent. Phys. Gesell., ■'> 

 (1903), No. .', pp. 50-59, figs. 3). — A method of estimating the hydrothermal equiva- 

 lent of the Berthelot bomb calorimeter is described, which the authors consider very 

 accurate. 



Platinum thermometers as a means of increasing the accuracy of calori- 

 metric measurements, W. Jaeger and II. vox Bteinwehb (Bit. Devi. Phys. Gesell., 

 5 (1903), No. 20, pp. 353-362, figs. 3). — The platinum thermometer for use with the 

 bomb calorimeter is described, which, according to the authors, makes for greater 

 accuracy. 



BOTANY. 



The influence of current electricity on plant growth, G. E. Stone (Massachu- 

 setts Sta. J!j>t. 19<>3, ]>}>. 18-30, figs. 2). — After briefly describing some previous inves- 

 tigations on the subject, an account is given of some experiments conducted by the 

 author under conditions resembling those which can be employed in commercial 

 gardening. The work was carried on in a greenhouse with radishes and lettuce in 

 boxes placed on movable trucks. The boxes were filled with a uniform quality of 

 soil, were thoroughly insulated, ami after using the soil for a few experiments it was 

 resifted and used again. 



With a few exceptions copper and zinc plates were used for electrodes, and the 

 radish seed was sown directly in the boxes, whereas the lettuce was transplanted to 



