11. E. Merwin — Per oxidized Titanium /Solutions. 121 



on in the paper, in connection with studies of the bleaching 

 agents. 



Temperature. — In solutions containing no bleaching agents 

 changes of temperature of 50° C. intensify the color 5 to 15 per 

 cent. In the presence of bleaching agents the color is inten- 

 sified by heating. In certain instances heating 10° C. restores 

 30 per cent of the color lost by bleaching. (See fig. 1, C.) 



Alkali sulphates. — The sulphate s6lutions used for the tests 

 were prepared chiefly from six lots of Baker's analyzed re- 

 agents-. Sixteen samples of sodium, potassium, and ammonium 

 carbonates, sulphates and bisulphates were employed. Several 

 of the samples were converted into pyrosulphates before test- 

 ing in order to expel any possible volatile impurity that might 

 bleach the titanium solution. However, such treatment had 

 but little effect. Definite amounts of sulphates, and of acid 

 were introduced into test solutions and the amount of bleach- 

 ing determined. The bleaching produced by equal molec- 

 ular proportions of the sulphates appears to be equal. 

 The amount of bleaching for potassium sulphate is indicated 

 approximately by the following table of averages from the 

 tests :* 



Sulphate Acid Bleaching 



grams cc. per cent 



•5 15 



2- 9 



8- 2 



•5 21 



2- 14 



Fluorine. — The percentage amounts of decoloration by 

 fluorine in test solutions of known acidity at 22° C. are shown 

 in fig. 1, B. For example, in a test solution containing 3 - 5 cc 

 of strong sulphuric acid, *0019 g. of fluorine causes a bleach- 

 ing of 30 per cent. The depth of the color of the solution is 

 then TO per cent of the original. Upon heating, the color is 

 restored as shown in fig. 1, C, g. At 70° C. the color is only 

 6 per cent less deep than in a standard solution at 22° C. 



Various compounds. — The effects i:>rocluced by the com- 

 pounds mentioned in this paragraph are given as determined 

 by Steiger and as verified or modified by the present experi- 

 ments. Aluminium sulphate has no marked effect on standard 

 solutions or on solutions bleached by alkali sulphates, but it 



* At least part of the bleaching in faintly acid solutions, attributed by 

 Dunnington to nietatitanic acid, was due to alkali sulphates. Steiger con- 

 cluded that alkali sulphates have little effect upon the color of solutions 

 bleached by fluorine. The probable slight excess of acid in his sulphate 

 solutions would account for his results. 



Am. Jour. Sci. -Fourth Series, Vol. XXVIII, No. 164.— August, 1909. 



