6 BULLETIN 163, U. S. DEPARTMENT OF AGRICULTURE. 



baths decompose upon standing in stoppered bottles, with the result 

 that hydrogen sulphid is formed, and the accuracy of the test is 

 consequently vitiated. The cause and mechanism of this change 

 calls for further study, but there is at present reason to believe that 

 it may be brought about through the action of microorganisms in the 

 bath. 



Obviously, if the outfit is used for testing concentrated dips, such 

 should first be diluted with sufficient water to bring the probable 

 content in sulphid sulphur to not much over 2 per cent. Such dilu- 

 tions may readily be made with the measuring cylinder and wide- 

 mouth bottle provided in the outfit. 



UTILIZATION OF RESULTS AFFORDED BY THE TEST. 



The object of using such a test as that described is to maintain 

 dipping baths at uniform and effective strength. The test merely 

 indicates the actual strength of the bath, and if the bath is found to 

 be too weak there then remains the task of calculating how much 

 concentrated solution must be added in order to bring it up to the 

 proper strength. Therefore the following tables * have -been pre- 

 pared to render the desired information obtainable with a minimum 

 of calculation. 



The use of the tables is very simple. For instance, suppose a 

 sheep bath amounting to 1,250 gallons to contain 1.1 per cent sul- 

 phid sulphur, as shown by the test, and suppose that a concentrate 

 containing 24 per cent sulphid sulphur (dilution figure 1 to 15) is to 

 be used to strengthen the bath. The table for standardizing sheep 

 baths shows directly that for every 100 gallons of bath in the vat 

 there is needed 1.8 gallons of concentrate, or for the whole, 12.5 X 

 1.8 = 22.5 gallons of concentrate, which quantity is simply to be 

 measured out and added to the bath already in the vat. However, 

 since the bath continually becomes weaker, it is advisable to add 

 somewhat more concentrate than just enough to attain standard 

 strength. 



i The formula used to calculate the figures in these tables is s=100 r — -, in which a=percentage of sul- 

 phid sulphur found in the bath by test; 6=percentage in the concentrate, and c=standard percentage 

 in bath for dipping. 



