408 



REPORT — 189i. 



an addition of 0'2 to 0'3 c.c. of silver solution gave a colour reaction.. 

 Dr. Bunte calculates that the priming must have been less than 01 per 

 cent. Both methods, therefore, showed that there was practically no 

 priming. Identically similar results were obtained in trials of four other 

 boilers. But in one trial there was considerable priming. In Trial IV., 

 on Siegel's Portable, the sample of boiler water taken at the beginning 

 showed 199 c.c. of 10 per cent, of normal salt solution, and that at the 

 end 191 c.c. per 100 c.c. This corresponds to a loss of 4 per cent, of the 

 salt in the boiler, or to 1'7 per cent, of priming. In the steam tests 

 different samples yielded 24-3, 20-3, 6-8, 4-0, 0-3, 0-2, 0-3, 25-5, and 7-3 c.c. 

 of 10 percent, of normal salt solution per 100 c.c. of condensed steam. 

 After thoroughly cleansing the apparatus by blowing through, 2,000 grams 

 of steam were condensed, and gave 9 c.c. per 100 c.c. The amount of salt 

 in the steam was therefore extraordinarily variable. The highest result, 

 25'5 c.c. per 100 c.c, corresponds to 12"8 per cent, of priming. Dr. Bunte 

 thinks that foaming occurred. 



It will be seen that in most cases the salt test fails to indicate any 

 appreciable priming. It must be inferred that the mechanical mixture of 

 boiler water with the steam is ordinarily an action of insignificant im- 

 portance. In one trial where there was great priming, shown by the 

 working of the engine as well as by the salt test, the results are extremely 

 discrepant, and apparently Dr. Bunte thinks that the real amount of 

 priming was greater than the salt tests indicate. 



The salt test was used in some tests of boilers at the Frankfort Exhi- 

 bition, in 1891, by a committee presided over by Dr. Schroter.' The tests 

 lasted eight days for each boiler. Salt was fed into the boiler till the 

 boiler water contained about 1^ per cent. After the boiler had been 

 working a day, two samples were taken, one of the boiler water from near 

 the evaporating surface, one from the nearest water separator in the 

 steam pipe. The samples were drawn off through a cooling coil to prevent 

 evaporation. The amount of salt in the samples was determined by the 

 nitrate of silver test, and also that in the feed supplied to the boilers. 

 The following table gives the results : — 



Determination of Priming hj Salt Test in Trials at the FranlifoH UxJdbition, 1891. 



These results are given chiefly to confirm the general result shown in 

 nearly all experiments — namely, that the amount of priming estimated 

 from a salt test is an insignificant percentage. 



Comparison of the Salt Methods with other Methods. — It is clear that 



' Engineer, June 8, 1894. 



