156 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 

 METHOD OF ESTIMATING COLOR IN WATEE. 



Mr. King, city analyst of Edinburgh, has published in 

 the Chemical JVeios a method of estimatins: color in water 

 for the purpose of determining the comparative turbidity of 

 different samples. This method consists in adding to a 

 known quantity of pure distilled water contained in a glass 

 tube an aqueous solution of caramel of a certain strength 

 until the tint communicated to the distilled water is found to 

 equal that of the water under examination. The tubes he 

 employs are made of perfectly colorless glass, fifteen inches 

 long, and of such a diameter that when filled to within three 

 inches of the top they will contain exactly eight ounces of 

 water. The depth of color which the distilled water and 

 caramel should exhibit is ascertained by adding ten grains, 

 by volume, of solution of ammonium chloride to eight ounces 

 of pure water, perfectly free from ammonia, in a glass tube, 

 forming a column twelve inches long. The ammonium 

 chloride solution should contain 3.17 grains of the salt in 

 10,000 grains of water. To this mixture, after proper agita- 

 tion, 25 grains, by volume, of Nessler's solution are to be 

 added ; and this, after mixing, is allowed to repose for ten 

 minutes at a temperature of 60 Fahr., when the color will 

 form 30 of Mr. King's scale; or, in other words, 300 grains, by 

 volume, or 30 (a degree being equal to ten grains by volume) 

 of caramel solution, if of proper strength, will produce exactly 

 the same depth of color when added to the same amount of 

 distilled water (eight ounces) in a column twelve inches long. 

 The caramel solution being thus prepared, in order to estimate 

 the color two tubes of the dimensions stated are to be filled to 

 within about three inches of the top, one with distilled water 

 and the other with water to be tested. The caramel solution 

 is then to be added to the distilled water until that is found to 

 equal in color the water contained in the other tube. Every 

 10 consumed will represent 1 of color. The intensity of the 

 color is ascertained by looking down through the length of 

 the column. 1 A, Jfarch 25, 1875, 133. 



FLUORESCENCE OF SOLUTIONS IN CASTOR-OIL. 



Some coloring matter derived from Avoods that do not show 

 any fluorescence when dissolved in water, alcohol, or other 



