28 MASS. EXPERIMENT STATION BULLETIN 369 



phenol 1 to 1000, oxyquinoline sulfate 1 to 1000, malachite green 1 to 10,000, 

 methyl alcohol, linseed oil, and shellac. Potassium permanganate solutions at 

 1 to 1000 and 1 to 100 seemed to have a stimulating rather than a toxic effect. 



DEPARTMENT OF CHEMISTRY 

 W. S. Ritchie in Charge 



Cooperative Analytical Service. (The Department.) 



Off-Flavored Eggs. Normal fresh eggs and those having a strong, "fishy" or 

 "sulfury" odor were sent in by the Poultry Department of the College for exam- 

 ination. Chemical analyses have failed thus far to show fundamental differences 

 in composition sufficient to account for the offensive odor. 



Insecticides and Fungicides. Various samples of flotation sulfur sent in for 

 examination were evaluated by a 300-mesh screen test and the character of the 

 residue. The samples varied from .07 to 4.06 in percentage of material that 

 would not pass a 300-mesh sieve. 



Roach Powder. A sample was analyzed qualitatively for active ingredient and 

 filler. The sample apparently contained sodium fluoride, a starch product, and 

 a water-insoluble coloring material. 



Lubricating Oil. Samples of new and used automobile lubricating oils were 

 submitted for analysis. The used oils were from cars and trucks equipped with 

 filters and represented various mileage. After extensive use these oils had "picked 

 up" considerable carbon, gasoline, and mineral matter and their effect on density, 

 volatility reaction, flash and fire points, and ash was considered a measure of 

 contamination. 



Some changes in the oils as a result of long-continued use were (1) increased 

 volatility (0.39 to 3.36 percent); (2) lowered flash point (442° to 265° F.); and 

 (3) increased ash content (0 to 0.38 percent). 



The used oils were treated with eight different clarifying agents and filtered. 

 Activated charcoal yielded a bright clear product superior in appearance to the 

 original unused oil. Bentonite also proved efficient but had less decolorizing 

 action. 



Testing Analytical Methods. (The Department.) 



Determination of Zinc in Foodstuffs. Work on the dithizone-carbamate method 

 for the determination of zinc in foodstuffs has been continued during the past 

 season with satisfactory results. The original "two step" method, published in 

 1938, has been improved by incorporating a preliminary treatment with dithizone 

 in an ammonical solution for the removal of nonreacting bases and acids and by 

 other minor changes to insure a more definite procedure. The use of wax-coated 

 bottles has reduced the contamination of the reagents but some of the synthetic 

 resins may prove more durable. 



Two samples, polished rice and seed rye, together with granulated zinc for 

 the standard were furnished various analysts under the auspices of the A.O.A.C. 

 for collaborative work. As a whole the technique was acquired more readily 

 than was expected, but adequate control was lacking in some instances due to 

 inexperience. Personal differences in reading a visual color comparator lead 

 to the belief that some of the new in.struments employing a barrier-layer type of 

 photoelectric cell would be preferable. 



Determination of Boron. The investigation of dark centers in rutabagas 

 necessitated a continued study of the Dodd method for boron. While this even- 

 tually gave concordant results, some modifications were necessary. Other methods 

 are now being studied with a view to securing a simpler process and one less 

 difficult to control. 



