802 EXPERIMENT STATION KECORD. 



Most of the sulphur reacts with tetrathionic acid to form pentathionic acid and 

 the remainder is in a colloidal solution. " The presence of pentathionic acid 

 was here shown in a similar manner on several of the mixtures, while they 

 still remained clear, by neutralizing with caustic alkali, using methyl orange 

 as indicator. As the neutral point was reached, a distinct opalescence ap- 

 peared which was not affected by hydrochloric acid, but which was dissolved 

 after a time by excess of caustic alkali." 



** For obvious reasons it is not likely that the reaction here noted, apparently 

 for the first time, will afford the basis for a desirable volumetric method for 

 use in the laboratory. It may be of value as a convenient means for reducing 

 arsenic acid to arsenious acid preliminary to precipitation by hydrogen sulphid. 

 As a basis for a field test, in default of anything better, it does offer some 

 promise, and exi)eriments in that direction are now under way." 



On the formation of hydrocyanic acid from proteins, H. W. Emerson, 

 H. P. Cady, and E. H. S. Bailey (Jour. Biol. Chem., 15 (1913), No. 5, pp. 415- 

 417). — Certain organisms, as for instance Bacillus pyocyaneus, will produce 

 hydrocyanic acid when grown on egg. The yolk seems to be a more favorable 

 medium for hydrocyanic acid production than the white. 



For the first experiments in this work eggs contaminated with bacteria were 

 broken, the whites separated from the yolk, and distributed into wide-mouthed 

 500 cc. flasks so that each flask contained either the whites or the yolks of 2 

 eggs. The flasks were loosely stoppered, put in a warm place, and tested each 

 day by the Schonbein test for hydrocyanic acid. Seventy-four experiments were 

 started in 9 different series, and in 8 experiments from 6 different series, after 

 intervals varying from 4 days to 14 days, the egg substance evolved hydrocyanic 

 acid. In a number of such cases crystals were obtained which looked like silver 

 cyanid although the silver nitrate was darkened by the hydrogen sulphid, but 

 the authors were not able to get positive results wnth the Prussian blue test. 

 The yolks developed hydrocyanic acid in 6 cases and the whites in 2 cases. 



Hydrocyanic acid was developed best when the organism was grown on a pro- 

 tein medium slightly acid to litmus and phenolphthalein. When hydrochloric 

 acid is present to an extent where it may be detected by the usual methods, 

 hydrocyanic acid is not produced. 



Preliminary report on the production of hydrocyanic acid by bacteria, 

 B. J. Clawson and C. C. Young {Jour. Biol. Cliem., 15 {1913), No. 3, pp. 419- 

 422). — ^A description of the biological features of one of the organisms isolated 

 in the investigation described above. It is shown that the power "which the 

 organism has of producing HCN is apparently not due to an extracellular enzym. 

 The organism was grown in gelatin for 72 hours at 37° C. and had been giving 

 off HCN for 48 hours. After filtering through a Berkefeld filter, some of the 

 filtrate was planted again into gelatin and incubated, but gave negative results 

 for HCN. Hydrocyanic acid gas is apparently produced only under aerobic 

 conditions, which led to the belief that the reaction in which HCN w%is produced 

 was due to oxidation of the proteins. This was subsequently shown to be 

 true. . . . Several other strains of Bacillus pyocyaneus were tested for HCN 

 production, all of which returned positive results." 



B. pyocyaneus was not the only organism capable of producing hydrocyanic 

 acid, as an unnamed organism isolated from the soil and a culture of B. vio- 

 laceus growing upon gelatin and egg produced it also. " There has been much 

 work done on the production of HCN from grain, beans, linseed meal, germinat- 

 ing Sorghum vulgare, and other protein-containing substances. In most cases 

 the production of HCN is attributed to an enzym. Apparently all of the workers 

 were using nonsterile material, which could have been easily contaminated by 

 an HCN-producing organism." 



