RECORD f< OF MEETIXaS 499 



of course, be an orange hue; that called "E.Y.B. 0-6-6*^ will be green, 

 while ^'E.Y.B. 6-0-6'' has a purplish hue. 



That the intensity of color of each of the three basic fluids is about the 

 same is shown by the fact that "E.Y.B. 4-4-4" closely approached both in 

 the "Co-Fe-Cu/' and in the ^^Co-Cro-Cu" series the ^^neutral gray/' which 

 is the nearest that blended reds, yellows and blues, can approach to pure 

 white in solids or transparent colorlessness in fluids. 



As to the permanency of these fluids, the original acidulated cobalt, 

 iron and copper solutions and their blends neither fade nor precipitate 

 to a perceptible degree until at least two years old: the ammoniacal co- 

 balt and chromium solutions have now been under observation for over a 

 year without any fading being detected. The ammoniacal copper, on the 

 other hand, unless kept sealed, precipitates and consequently undergoes 

 color change after a few weeks. However, the ammoniacal copper solu- 

 tion is in practice prepared extemporaneously by diluting the permanent 

 half-normal acidulated copper solution to fiftieth-normal strength by 

 addition of ammonia water and water, hence the preparation of the "Co- 

 Cro-Cu''' blends is merely a matter of mixing solutions that can be kept 

 in stock for months without deterioration. 



As to the practical application of these fluids, it has been found that 

 in a properly conducted ISTessler test an ammonia dilution representing a 

 nitrogen content of 1 to 500,000 matched the ''Co-Fe-Cu'' blend 3-9-0, 

 when this half -normal mixture was diluted to "50 per cent'^ of its origi- 

 nal strength by addition of an equal volume of water; that the color of 

 the phenol-sulphonic acid test for nitrates, when the nitrogen content 

 was 1 in 500,000, was matched by "Co-Fe-Cu" blend 0-12-0 when this 

 was diluted to ^'66 per cent.'' strength; that the molybdate assay for 

 phosphoric acid, 1 in 20,000, gave a yellow color exactly matched by "Co- 

 Cro-Cu 0-12-0" diluted to ^*15 per cent." strength; that Folm's vanillin 

 test, when the vanillin content was 1 in 100,000, gave a color matched 

 by "Co-Cro-Cu" blend 3-3-10 ; that Eiegier's uric acid test of a uric acid 

 content of 1 in 40,000 had the same tint as "Co-Cro-Cu" blend 2-2-8, 

 and that a salicylic acid dilution of 1 in 50,000, when treated with the 

 proper amount of ferric chloride solution, produced a color exactly 

 matching "Co-Cro-Cu" blend 7-1-5 that had been diluted to 65 per cent, 

 strength. 



The two sets of colored fluids "Co-Fe-Cu" and "Co-Cro-Cu" fail 

 when it comes to certain shades of red. Thus the color produced in the 

 naphthAdamine-sulphanilic acid test for nitrites had no match in the 

 pink fluids of the two sets of standard blends. This led to the study of 

 other possi])le standard fluids that would supply the hues not attained by 



