16 



FARMEES' BULLETIN 603. 



All example may make the whole operation clearer. Taking the vat aires 

 used to illnstriite the method of obtaining total capacity (p. 14), we first m£ 

 the' following table of dimensions: 



Vat. 



At full 

 depth. 



At three- 1 

 quarter- j 

 depth. 



W ater-Iine length . 

 Water-line width. 



Bottom length 



Bottom width 



Depth 



Second, we calculate the capacity at three-quarter depth (3.94 feet) to b<j 

 056 gallons. From Table 3, 0.94 foot is found to be equal to 11^ inches; hence[ 

 at 3 feet 11^ inches from the bottom end of the rod is made the mark for 

 capacity of 956 gallons. 



Third, knowing the full capacity to be 1,491 gallons; 1,491—956=535 gallonsj 

 or 5.35 hundreds of gallons space in the vat between the three-quarter and full] 

 depth le>v..o, which corresponds to 5.25-^-4=1.31 feet difference in depth 

 1.31-^5.35=0.245 foot per 100 gallons. 



Fourth, 1,000—956=44 gallons; ^ X0.245=0.108 foot, corresponding to 

 gallons. From Table 3, 0.108 foot=li inches (nearly), so on the rod li inches 

 above the mark for 956 gallons is made a mark for 1,000 gallons. Then, fronj 

 the 1,000 gallons mark is measured off 0.245 foot=3 inches for 1,100 gallons; 

 2X0.245=0.49 foot=6 inches for 1,200 gallons, etc. 



The graduations necessarily depart a little, though not much, troni 

 the true points for levels between the fixed points established by cal-j 

 culation. One may, if familiar with the process of " plotting," laj 

 off these fixed points from depths on one axis and capacities on the 

 other, and so construct the " curve " of the capacity of the vat. 



THE SAFE DISPOSAL OF WASTE ARSENICAL BATHS. 



Previous publications of the department have advised that whei 

 vats are emptied for cleaning, the waste dip should not be flowed ovei 

 land or vegetation to which domestic animals have access, or froi 

 whence it may find its way into water supplies, but should preferabb 

 be run into a properly located pit protected by a fence. 



Dalrymple and Kerr ^ have proposed to add slaked lime and copj 

 peras to waste dip in the vat in order to throw down arsenic in ai 

 insoluble form, thus allowing the overlying liquid, after settling, tc 

 be disposed of as if arsenic free. The method re(]uires very thor-| 

 ough stirring in order that the difficultly soluble lime may product 

 the desired effect. Wliether the necessary stirring can be accom- 

 plished in large vats with sufficient thoroughness to render th« 

 method reliable under practical conditions on a large scale may bt 

 questionable. 



» Bulletin 13L', Louislanii .\t;rlcultur!il Kxporiniont Station, 1011. A luloC dotiUIc(! 

 description of the nii'tliod is given In Fiirnicrs' Bullotin ■\'.)S and in Hureau of .\ulnie 

 Industry Circular 207 of the I'. S. Department of .Vgriciiltuio. 



o 



WA.SIIINOTON : GGVKUNMK.N'T PRINTING OmCB : 1014 



