428 AXXALS XEW YORK ACADEMY OF SCIEXCES 



produced Trhich consist of lime and organic matter. After the precipi- 

 tated matter has been allowed to settle, an ejfflnent is obtained which is 

 clear, colorless and free from suspended matter. The bacterial content 

 is low. o-enerallv onlv a few hundred, and decreases on standing:. The 

 dissolved oxygen is high and very rapidly rises to about SO per cent. 

 There is no odor whatever, the effluent being entirely stable and suitable 

 for discharge into any stream. There is no odor or nuisance whatever 

 about the plant, which may be placed at any sewer outlet. About one- 

 haK ton of lime is used per million gallons of sewage, the cost of lime 

 and electric current being about $10 per million gallons of sewage. 



Professor Arny gave a demonstration consisting of an exhibition of 

 three sets of standard colored fluids, designated as the '"Co-Fe-Cu/"' the 

 "Co-Cro-Cu"' and the "Cro-Manganate" blends. 



The "Co-Fe-Cu*' tints have as their basis red acidulated half-normal 

 cobalt solution containing 59.49 grammes of cobalt chloride C0CL6H0O 

 to the liter, the solvent being 1 per cent, hydrochloric acid : yellow acidu- 

 lated half -normal ferric solution, containing 45.05 grammes of ferric 

 cliloride FeClgGH^O t-o the liter, the solvent being 1 per cent, hydro- 

 chloric acid and blue acidulated half -normal copper solution containing 

 62.43 grammes of copper sulphate CuSO^SHoO to the liter, the solvent 

 being 1 per cent, hydrochloric acid. 



The ^'Co-Cro-Cu** tints are prei^ared from ammoniacal solutions of the 

 three elements mentioned, the solvent in each case being 2.8 per cent, 

 ammonia water. These consist of red ammoniacal fiftieth-normal cobalt 

 solution containing 2.? grammes of roseo-cobaltic chloride COClgoXHg- 

 HoO to the liter: yellow ammoniacal fiftieth-normal chromium solution 

 containing 0.420 grammes of ammonium dichromate (XH4')2CroO- to 

 the liter ; blue ammoniacal fiftieth-normal copper solution containing the 

 equivalent of 2.496 grammes of copper sulphate to the liter. Details con- 

 cerning the preparation of these ^'Co-Cro-Cu^' fluids and their blends 

 will be found in an article by H. V. Arny and C. H. Eing in the Journal 

 of the Franklin Institute for August. 1915. 



The blending of the acidulated fluids to make the "Co-Fe-Cu"' tints 

 and of the ammoniacal fluids to make the '^Co-Cro-Cu'" hues can, of 

 course, be performed in any proportion that fancy suggests. The 91 

 samples of each series which were exhibited included the possible blends 

 produced in making 12 c. c. of flnished fluid when the ingredients are 

 mixed in even (non-fractional) cubic centimeter quantities. The nomen- 

 clature devised is of the simplest kind. Thus the original red fluid is 

 '•E.Y.B. 12-0-0.'' the original yeUow is •'•'!?. Y.B. 0-12-0"' and the original 

 blue is "E.Y.B. 0-0-12.'* The sample designated as "E.Y.B. 6-6-0'' will, 



