DISEASES OF SHEEP 557 



about one hour, after which 3 Ibs. of copperas, in warm solution, 

 were added. The clear solution remaining on top in the receptacle 

 was tested about 15 hours later, and with no trace of arsenic what- 

 ever. 



In order to make the calculation as simple as possible, it may 

 be figured out for each hundred gallons of the arsenical solution left 

 in the dipping vat at the time it is to be cleaned. For this quantity 

 of solution, 6 Ibs. each, of air-slacked lime and commercial copperas 

 should be ample, as it was calculated to an excess. Or, in other 

 words, for each 100 gallons of the arsenical solution left in the vat, 

 6 Ibs., each, of air-slacked lime and common commercial copperas 

 should be used. 



In building concrete dipping-vats, it would be well to have 

 marks on the inside indicating each one or two hundred gallons, so 

 that a more or less accurate estimate could be made of the remain- 

 ing solution at any time. Or, when a vat is being filled, the water 

 could be measured as it is put in, and a measuring-stick marked, 

 after each 100 or 200 gallons had been added, which could after- 

 ward be used for a similar purpose. Or, the quantity of solution 

 could be ascertained by the use of the following rule: 



Measure, in inches, the length at the top of the solution, and 

 also at the bottom of the vat. Add these two numbers together and 

 divide by 2 to get the average length. In the same way measure, in 

 inches, the top width of the solution, and the width of the bottom of 

 the vat, and divide by 2 to get the average width. Then measure 

 the depth of the solution in inches. Multiply the average length by 

 the average width, and multiply the result by the depth. Divide 

 the last result by 231, and the answer will be the number in gallons 

 of solution left in the vat. 



Presuming that the quantity of solution left in the vat, includ- 

 ing the sediment composed of manure and mud, should be 500 

 gallons. This would take 30 Ibs., each, of air-slacked lime and cop- 

 peras. After adding the lime, the mixture should be thoroughly 

 agitated, or stirred, and allowed to stand for at least one hour. The 

 copperas should first be dissolved in hot water, and while still hot, 

 should be added, somewhat slowly, to the contents of the vat, and 

 the whole again stirred and then permitted to remain still for ten or 

 twelve hours, or over night. At the expiration of this time, the clear 

 solution on top may be syphoned or pumped to any convenient 

 place without danger, as it should contain no arsenic whatever; and 

 the precipitate, or sediment, afterward removed and buried in a hole 

 or small pit, if thought necessary, although it, too, should be harm- 

 less, or inert, as the arsenic has been changed to a condition that is 

 insoluble in water. 



SUMMARY. 



Unless carefully disposed of, the arsenical dipping solution 

 taken from the vat previous to cleaning the latter may be a source 

 of danger in contaminating the water supply, or vegetation, al- 

 though, up to the present, accidents from this cause have not been 

 brought to the attention of the writer. 



