I9I3] Alfred P. Lothrop 553 



rhamnose, xylose, galactose, glucose, fructose, maitose, and lactose 

 promptly reduce alkaline sodium selenite. A selenite reagent con- 

 taining 2 per cent. sodium selenite, 10 per cent. sodium citrate and 

 10 per cent. sodium carbonate has thus far been as efficient as the 

 Fehling-Benedict reagent. 



Selenium Compounds are toxic to both plants and animals. 

 Beginning with the most poisonous, the sequence of toxicity for the 

 group selected was the f ollowing one : hydrogen selenide, selenium 

 dioxide, selenic acid, sodium hydrogen selenite, sodium selenite, 

 potassium selenocyanate, sodium selenate, free selenium. Intra- 

 venous injection is followed by a marked fall in blood pressure; 

 potassium selenocyanate, however, induces a considerable rise. Pul- 

 monary edema, accompanied by exudation of large volumes of 

 yellowish fluid, preceded death in the case of selenium dioxide, 

 sodium acid selenite, sodium selenite and selenic acid. Respiratory 

 paralysis set in before the heart stopped. 



Reduced selenium can be detected in neutral urine by the addi- 

 tion of potassium Cyanide. Decomposition by means of hydro- 

 chloric or sulfuric acid of the potassium selenocyanate thus formed 

 results in the production of a colloidal Suspension of brick-red 

 selenium. Potassium selenocyanate can be detected by the addition 

 of ferric chlorid, followed by a drop of dilute sulfuric acid Solu- 

 tion. The presence of potassium selenocyanate in the urine inter- 

 feres with the Fehling-Benedict reduction test. The study is in 

 progress. 



10 1. The influenae of electrolytes on the precipitation of 

 soluble starch.i^ Helen I. Mattill and H. A. Mattill. The 

 origin of this investigation was an Observation by Dr. Gies that 

 Solutions of soluble starch, when dialyzed free from electrolytes, 

 were not precipitable by alcohol, and that the addition of a drop of 

 dilute Salt Solution restored precipitability. It was the object of this 

 work to determine at what concentrations of electrolyte the precipi- 

 tation by alcohol ceased, i. e., how delicate a test for electrolytes it 

 is, and how variations in the nature of the electrolyte affected the 

 reaction. Two percent soluble starch Solutions were dialyzed until 

 they gave no precipitate upon the addition of alcohol. Two c.c. of 



1^ Some of the work was done in the Physiological Laboratory at the 

 University of Utah, where it is now in progress. 



