PRESIDENTIAL ADDEESS. 7 



Its agricultural value has been found to be equal to that contained in Thomas precipitate 

 or bone ash. "With reference to price, it is calculated that one pound of phosphoric acid 

 contained in the finely ground basic slag can be delivered for about one penny. If we 

 take the value of 80 p.c. apatite in Liverpool at lOd. per unit, or about id. per pound of 

 tribasic phosphate, then the price of phosphoric acid in it amounts to 0.97d., or say Id. per 

 pound. This is the same price as in the ground slag, but a great difference lies in the 

 fact that, while the slag is ready for the uses of the farmer, the apatite is not, and its 

 phosphoric acid has still to bear the cost of manufacture. One pound of phosphoric acid 

 contained in high grade superphosphate made from Canadian apatite, cost in 1886, in Lon- 

 don, 2.4d. From this and from the experience gained in Scotland and Grermany, regard- 

 ing the relative agricultural value of soluble, precipitated and slag phosphate, it seems 

 plain that making SM/>e/-phosphate will soon become a thing of the past and that our 

 apatite miners will require to seek some new method of applying their mineral to agri- 

 culture, so that it may be able to compete with its new rival, the Thomas-Gilchrist slag. 

 This is a problem to which our chemists and agriculturists should address themselves 

 with the least possible delay. Very likely, by melting apatite with basic fluxes, and 

 grinding the product extremely fine, a material might be produced capable of direct 

 and advantageous application to crops. 



The history of the soda industry for the last thirty years furnishes numerous brilliant 

 instances of waste saviug, but to describe them would lengthen this address unduly. I 

 shall merely point out briefly the bye products of this manufacture which were wasted 

 previous to 1847, and state whether they are being utilised at the present day. 



I. The residue from burning iron pyrites, in making sulphuric acid, was a waste pro- 

 duct together with its contents in cojiper. The latter metal is now recovered by the 

 Henderson or humid process, and large quantities of the lixiviated residue are used in 

 the iron manufacture, as "" fettling " or lining for the puddling furnaces, and to act as flux 

 in the basic Bessemer process. 



II. Prior to 1847, large qiaantities of the hydrochloric acid, produced in converting 

 salt into sulphate of soda were allowed to escape into the atmosphere, and this continued 

 in lesser measure until the Alkali Act was i)assed in 1863. Now, none of this hydro- 

 chloric acid escapes condensation, but still a certain proportion of it is allowed to run to 

 waste, owing to the fact that the consumption of chlorine products bears a lower pro- 

 portion to the soda products than the quantity of chlorine bears to that of sodium in the 

 salt. 



III. Then, all the manganic oxide used for the production of chlorine found its way 

 into the sewers ; now, it is all recovered and used over again by the Weldon process. 



IV. Then, as now, it was not possible to obtain more than one-half of the chlorine 

 contained in hydro-chloric acid in a state available for mauu.facturiug bleaching powder : 

 the balance found and finds its way to the sewers as chloride of calcium. 



V. Then, the " tank waste " or sulphide of calcium resulting from the lixiviation of 

 black ash was thrown aside as useless, and the same state of matters exists at the present 

 time. For although processes have been perfected for recovering the sulphur from this 

 waste, the present low price of sulphur in Spanish pyrites renders them unremunerative. 

 The cost of this sulphur to the British chemical manufacturer has fallen in the last ten 

 years from 5|d. to 3d. per tinit. 



