40 ART. 15— TAMEMASA HAOA. 



Taken. Found. 



Trisulphonate, 2-580 2*547 2-G24 



Sulphate, '347 -380 -.373 



Disulphonate, -G22 -629 '551 



Nitrite, -208 «212 '217 



From this experiment, it seems that the sulphate may come out nearly 

 10 percent, too high, no doubt for two reasons; one that, being 

 precipitated in the cold, the barium sulphate retained other salts with 

 it ; the other and principal reason being that, in ihe process of 

 neutralising the solution, some of the disulphonate must be decompos- 

 ed, yielding sulphate. The numbers for the trisulphonate are much 

 more satisfactory, being less than 1.7 per cent, too high, apparently 

 because they represent the difference between two sulphate determina- 

 tions, the error in the one counterbalancing the corresponding error 

 in the other. When, however, ayc come to the numbers for the 

 disulphonate, which are calculated from those for the other substances, 

 it is seen how large the error may become, being in one case as much 

 as 11*4 per cent, too low. Similarly, the quantity of nitrite calculated 

 from those of the other substances may come out as much as 4'5 per 

 cent, too high. The expression of the errors as percentages only 

 holds good, of course, where the salts in an actual experiment are 

 nearly in the same proportions as here taken, as they were generally 

 found to be. 



The quantities of nitrite and of gases yielded by the peroxyl- 

 aminesulphonate may also be each determined directly. The nitrite 

 may be estimated by the urea, method, as .stated on page 24, most of 

 the sulphonate salts having first been crystallised out and washed 

 with alcohol. The method for collecting and measuring the gases 

 produced during the decomposition consists in Letting this proceed in 

 a closed vessel from which ihe air is withdrawn. A stout- walled, 



