266 EXPERIMENT STATION RECORD. 



clde made from crude curbolic acid had been prepared, its particular advantages 

 being cheapness, high larvacidal and germicidal powers, miscibility with water, 

 and relative imiform composition. The work of destroying the algae and mos- 

 quito larvae in the Canal Zone requires an average of 2oU bbls. per month, and 

 a plant for its manufacture has been in operation for over 2 years. 



To make the iarvacide 150 gal. of crude carbolic acid of a specific gravity not 

 greater than 0.97 and containing not less than 30 per cent tar acids " are heated 

 in an iron tank having a steam coil with steam at 50 lbs. pressure. Two hun- 

 dred lbs. of finely crushed and sifted common resin are dissolved in the heated 

 acid and then 30 lbs. of caustic soda dissolved in G gal. of water are added. 

 There is a mechanical stirring rod attached to the tank. The product is ready 

 in a few minutes, yielding about 3J bbls." 



Its cost is shown to be*14.13 cts. per gallon. "The germicidal value when 

 tested with B. typhosus in an aquesous emulsion of the Iarvacide has an R-D 

 coefficient of from 2 to 5. As a mosquito Iarvacide it is used by spraying an 

 aqueous emulsion (1 part of Iarvacide to 5 of water) over the surface and 

 along the margins of pools and ponds or other mosquito breeding places so 

 that the resulting dilution of the Iarvacide has a thin milky opalescence repre- 

 senting approximately a dilution of 1 : 5,000." 



Anopheline larvae are said to be slightly more resistant than Culex larvae 

 and all pupae are more resistant than larvae to the effects of this Iarvacide. 



The author believes that the theory of Chick and Martin <^ that the removal 

 of an emulsion of tar acids by bacteria is a process of adsorption and not a 

 chemical combination and that disinfectants of this class possess superior effi- 

 ciency because owing to this adsorption the bacteria rapidly become surrounded 

 by the disinfectant in much greater concentration than exists throughout the 

 liquid, holds true for algae and protozoa. " When emulsions of Iarvacide are 

 put up with large quantities of algae, such as spirogyra, the Iarvacide loses its 

 turbidity, 50 per cent being lost in some concentrations within 2 hours. Micro- 

 scopic examinations fail to disclose a cause for this loss of turbidity." 



A table which gives the hour after exposure at which anopheline larvae 

 either die or pupate shows that the efficiency of the Iarvacide will last for over 

 7 days. It also shows that when in contact with algae for a period of 1 to 7 

 days, 70 per cent of the larvae are destroyed within 48 hours. " The Iarvacide 

 hastens pupation, and the algae control shows that when larv£e are placed in 

 contact with fresh algae and fresh water the larvae pupate naturally for several 

 days ; decomposition, however, sets in after 110 hours with the formation of a 

 pellicle of bacteria and protozoa on the surface. The anaerobic conditions be- 

 neath the pellicle cause the death of algie and larvjie." 



FOODS— HUMAN NUTRITION. 



A report on the milling' properties of Idaho wheat, J. S. Jones, H. P. 

 FisHBUKN, and C. W. Colvek (Idulio ista. Bui. 7^, pp. 65, pis. 2). — Owing to the 

 belief that northwestern grown wheats have a comparatively low milling value, 

 which doubtless materially affects their price in certain markets, extended 

 studies were made of the physical properties, weight per bushel, protein con- 

 tent, and milling value, as well as baking tests under laboratory and home 

 conditions. 



The Idaho wheat crop, it is pointed out, consists of a number of varieties 

 grown under very varied conditions, only 3 or 4 being common to north and 

 south Idaho, the two sections of the State where the contrast is greatest in 



".Tour. Hyg. [Cambridge], 8 (190S), No. 5, pp. 69S-703. 



