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



On the inside of the cover of the case is glued a printed instruction 

 sheet, protected by a pyroxylin varnish, which reads as follows : 



United States Department of Agriculture. 

 Bureau of Animal Industry. 



TEST OUTFIT FOR LIME-SULPHUR BATHS. 



1. Mix bath well, let settle for a few minutes, then fill clean, dry graduate with 

 bath, setting top edge of surface on the zero mark, and pour (draining out drops) into 

 clean, wide-mouthed bottle. 



2. ftinse graduate with clean water (or with a little of the test fluid) shake out 

 adhering drops, and fill to zero mark with test fluid. 



3. While gently swirling bottle containing the bath pour in test fluid from the 

 graduate until the yellow color of the bath becomes faint. Then let the contents of 

 the bottle come to rest and gently drop on the surface one drop of indicator solution 

 from the dropping bottle. Note if a violet color appears where the indicator solution 

 mixed with the bath. If color appears add a little more test fluid from the graduate, 

 mix, and test again with a drop of indicator solution. Continue thus until a drop of 

 indicator solution fails to produce any color, avoiding the addition of excess of test 

 fluid. 



The number of cubic centimeters of test fluid added to just reach the point where 

 color with indicator solution fails to appear represents tenths of one per cent of "sul- 

 phid sulphur" in the bath. 



Note. — The indicator solution should not be more than one week old. Prepare 

 fresh solution by dissolving one "tablet for indicator solution" in 15 c. c. clean water 

 in the bottle. 



II. The utensils. — Bottle A' } fitting into compartment A of the 

 case, is an ordinary 3-ounce wide-mouth bottle of clear glass. 



Measuring cylinder C , fitting into compartment 0, may be of 

 ordinary type though preferably it is graduated to read down only, 

 and is provided with an especially deep lip to prevent the liquid from 

 running down the outside when small quantities are poured out. C" 

 is a bristle brush for cleaning. It will be noted that the partitions of 

 compartment are cut away as indicated to admit the foot of the 

 cylinder. At the point (p) on the back wall of the case is cemented 

 a f-inch pad of cork to protect the cylinder from breakage. The 

 brush G" is put into compartment <7 after the cylinder, thus protect- 

 ing the latter from contact with the cover of the closed case. 



III. The reagents. — The "test fluid," — that is, the standardized 

 iodin solution — is contained in the bottle D' , which may be a special 

 square bottle to fit compartment D, or, more readily obtainable, a 

 4-ounce standard-shaped "sample oil" bottle, preferably of amber 

 glass, and provided with a "flat-hood" glass stopper. The test fluid 

 is of such strength that in the actual performance of the test each 

 cubic centimeter of it employed represents one-tenth of 1 per cent of 

 sulphid sulphur in the bath. Allowing for the meniscus, etc., it 



