24 report — 1877. 



The plan should bo adopted of combining the strongest metal with the 

 strongest salt radical, after due allowance for the tendency to form insoluble 

 or nearly insoluble salts. Thus the soluble calcium should always be stated 

 as existent as sulphate. The excess of the salt radical should be combined 

 with potassium on the ground that chloride, nitrate, or carbonate of potassium 

 is incapable of coexistence with sodium sulphate. 



In the case of artificial or acid sulphates, produced by treating " muriates" 

 with vitriol, the Committee is of opinion that the free acid is sulphuric acid, 

 not hydrochloric acid. The reason for this opinion is to be found in the fact 

 that any free hydrochloric acid would inevitably have been volatilized at the 

 temperature employed in the production of the sulphate. The same remark 

 applies to sulphuric acid if actually free, but if in combination with sulphate 

 of potassium, to form an acid salt, it might resist volatilization. The acid 

 salt here mentioned as a compound of sulphuric acid and sulphate of potas- 

 sium would be more correctly described as potassium-hydrogen-sulphatc, 

 KHSOj but your Committee believes that the practical inconvenience of 

 stating a certain amount of potassium in this form and the rest as neutral 

 sulphate would outweigh any advantage to be derived from a scientifically 

 exact statement*. 



It is evident that the presence of free sulphuric acid or of an acid sulphate 

 in artificial sulphates can only be due to imperfect admixture of the vitriol 

 and muriate, otherwise the following well-known reactions would havo taken 

 place : — 



KIISO, + KC1 =K 2 S0 4 +IIC1. 

 NaHS0 4 + NaCl=Na 2 S0 4 + IIC1. 



In the event of the bulk of the muriate consisting of chloride of potassium, 

 it may be argued that there is a greater probability of that salt remaining 

 unacted on than that chloride of sodium should remain undecomposed ; but it 

 is evident that the circumstances are such as must vary with the conditions of 

 each case; and your Committee therefore prefers to recommend the adop- 

 tion of the arbitrary assumption that all potassium exists as sulphate, pro- 

 vided that there is sufficient of the salt radical present to combine with the 

 whole of the potassium, after allowing for the free acid and the sulphate of 

 calcium. 



On the other hand, it may be argued that as sulphates are always converted 

 into carbonate or caustic alkali, any chloride present in the sample would 

 ultimately be lost in the worthless form of chloride of potassium, whatever 

 the metal with which it was originally combined. This argument has con- 

 siderable force, and to meet it the Committee recommends that all statements 

 of the results of analyses of artificial sulphates should have appended the 

 equivalent in chloride of potassium of the chloride found. In artificial sul- 

 phates there is considerable probability that the chlorino exists chiefly, if 

 not wholly, as potassium chloride ; but such cannot be assumed to be the 

 case with other sulphates, and in the statement of the composition of those 

 the Committee considers the above calculation undesirable from a scientific 

 point of view, though it is clear that there are other considerations in its 

 favour. 



The distribution of the salt radicals among the remaining metals (sodium, 

 magnesium, and iron) appears to the Committee to be a matter of indifference, 



remark applies to other double salts, such as MgSOj-^-K.SO,,, and (lie 

 ind SK.SOjXiS'a.SO,, often met with in kelp products. The recognition 



* The same 

 curious eouipouni 



of the presence of such compounds in the statement of the results of analysis of com- 

 mercial s-Jts containing them appears to the Committee to be quite unnecessary. 



