BUREAU OF Al^IMAL INDUSTRY. 127 



DIPS AND DISINFECTANTS. 



The laboratory of dips and disinfectants received for examination 

 131 samples of stock dips, disinfectants, and miscellaneous materials. 



During the calender year, 1918, there were sent to inspectors in 

 the field 804 test outfits for arsenical dips and sufficient supplies for 

 making 584,500 tests: 9 test outfits for lime-sulphur dips and sup- 

 plies sufficient to make 3,200 tests; 13 test outfits for nicotin dips 

 and supplies sufficient for making 2,970 tests. There were thus pro- 

 vided a total of 82G new testing outfits together with supplies suffi- 

 cient to make a total of 590,670 tests. 



In research work a comparison was made of the relative advan- 

 tages of arsenious oxid and iodin, both of high purity, as standard 

 substance* in iodimetry. The residts were published m the 'Journal 

 of the American Chemical Society (vol. 41, p. 351). 



Considerable work has also been done on a study of methods for 

 evolving gaseous formaldehyde for disinfecting purposes, and it 

 appears that less expensive methods than the potassium permanga- 

 nate method will be found appropriate. This work is being con- 

 tinued. 



Of the various substances used in dipping animals the compound 

 cresol solutions are the only ones for which no suitable field test is 

 available. The field test, which aJffords a means by which the in- 

 spector in the field may assure himself that the dipping bath after 

 completion is of the proper strength, is considered highly important 

 in carrying on field dipping operations successfully. For that rea- 

 son considerable study has been given to the development of a 

 method for testing cresol solutions in the field. A method of field 

 testing has been devised which appears to be sufficiently promising 

 to warrant an early trial of it in the field. 



The laboratory has also carried on experiments to find a substitute 

 for linseed oil, which is now scarce and high priced, and which has 

 been required heretofore in the preparation of compound solution 

 of cresol and of saponified cresol solutions. It has been determined 

 that soy-bean oil, or the fatty acids derived therefrom, are well 

 adapted for the purpose and may be used at a considerable saving 

 in cost. 



Some additional work has been done upon problems relating to the 

 disinfection of hides and of tannery effluents, relating particularly 

 to the effect of heat and of chlorin upon anthrax spores in the effluent 

 from soak vat?. The results obtained do not differ materially from 

 those heretofore reported. 



A comparative study has been made of the germicidal value of 

 Dakin's solution, eusol, chloramine T, and chlorin in aqueous solu- 

 tion. 'This work indicates that these different disinfectants vary in 

 their action upon different microorganisms. A study has been made 

 also to determine the effect of lime upon the germicidal efficiency of 

 phenol and cresol. Lime seems to lower distinctly the germicidal 

 value of both of these disinfectants. 



RESEARCH WORK ON MEATS AND MEAT PRODUCTS. 



The nature of the research work on meats was changed in order 

 to meet war conditions, and investigations that had been undertaken 

 with a view to the conservation of materials used in the curing of 



