192 EXPERIMENT STATION KECOED. 



cular describes two portable machines for tlie generation of hydrocyanic acid 

 gas for fumigation and reports a study of the accuracy of the machine method 

 as compared with pot generation. 



The first machine consists of a cylindrical drum within which there is a tray 

 suspended. Mounted above the drum are two reservoirs for sulphuric acid and 

 cyanid solution, respectively. These solutions are measured in cylinders and 

 are then run within the drum. The gas is very quickly generated and by its 

 own pressure forced through the outlet hose under the tent. The chief differ- 

 ence in principle of pot and machine generation is that in the machine the 

 cyanid is added in solution instead of in the solid form as in the pots and the 

 generation, therefore, takes place much more quickly. 



The second machine consists essentially of two tanks, one above the other. 

 In the lower tank is placed the sulphuric acid and water, in the upper one the 

 cyanid solution. By the action of a suitable pump measured quantities of the 

 cyanid solution are forced into the tank containing the acid and water and the 

 gas is generated almost instantly and discharged through the delivery hose 

 with considerable force. The basic principle involved is that small successive 

 quantities of cyanid solution are added to a large amount of acid and water 

 until the acid is nearly exhausted. 



The drip from the delivery hose of the second machine was analyzetl for 

 over 300 charges without finding a trace of sulphuric acid. The experimental 

 results showed the high and uniform percentage of gas evolved when the latter 

 machine was working with fairly high charges at short intervals. Almost as 

 satisfactory results were obtained with a longer interval. "A rate of 30 

 charges per hour is probably as slow as it is wise to run the machine and with 

 small charges this is too slow." With 4-oz. charges a smaller, but still efficient, 

 amount of gas developed. " The best production of gas is obtainetl with a high 

 temperature. It is extremely important to keep the cyanid solution and tank 

 scrupulously clean. Any dirt or small bits of wood may interrupt the pump 

 and so make the charges irregular. Under normal conditions with clean solu- 

 tions the pump works with great regularity." 



The silo in California agriculture, F. W. Woll {California Sta. Circ. 138 

 (1015), pp. 23, figs. 7). — This circular gives general information in regard to 

 silo construction, silage crops, and the feeding of silage, with special reference 

 to California conditions. 



The construction of poultry buildings, J. Hadlington (Dept. Agr. N. S. 

 Wales, Farmers' Bid. 100 (1915), pp. 15, figs. 8). — This bulletin describes and 

 illustrates the continuous-house principle for poultry buildings, a combined 

 roosting and scratching shed, and the colony system, with specifications. 



Standards of ventilation in the light of recent research, C. E. A. Winslow 

 (Science, n. ser., Jt2 (1915), Xo. 1080. pp. 358, 359).— T\n<^ is an abstract of a 

 paper presented at the recent meeting of the Society of American Bacteriolo- 

 gists reviewing the investigations of the New York State Commission on Venti- 

 lation previously noted (E. S. R., 34, p. 70). 



Ventilation in its relation to air-borne diseases, A. C. Abbott (Science, n. 

 ser., 42 (1915), No. 1080, p. 358). — This is an abstract of a paper presente<l at 

 the recent meeting of the Society of American Bacteriologists reviewing various 

 observations which have been made on this subject. The author reaches the 

 conclusion that ventilation has nothing whatever to do with either the trans- 

 mis.sion of the so-called "air-borne" diseases or the lessening of their trans- 

 mission. He is of the opinion "that transmission by way of the air.- strictly 

 six-aking. is of Infinitely less importance than transmission by animate and 

 inanimate carriers that have been in intimate contact with the patient." 



