ON THE ESTIMATION Ol' POTASH AND PHOSPHORIC ACID. 25 



the Committee by filling up the accompanying paper, and returning it to mo 

 at your earliest convenience. 



"A similar paper has been sent to all the Fellows of the Chemical Society ; 

 but if you know any other Chemists, whose advice and opinion would be of 

 service to the Committee, we shall esteem it a favour if yoa will kindly 

 send me their names. 



" I have the honour to be, 



" Your obedient Servant, 



"Alfked H. Allen, 

 Hon. Secretarrj of the Committee.'" 



Together with the above circular letter, the Committee forwarded the 

 following series of very carefully arranged questions, with the view of indi- 

 cating the exact nature of the information they were in need of. 



] . Will you give the Committee the details ~| 



I 



of the process you habitually employ 

 for the estimation of the Phosphoric j 

 Acid in Commercial Phosphates ? J 



r 



2. What length of time does the above 

 process require ? 



Are you of opinion that the method ' 

 gives strictly accui-ate results? If not, 

 will you state the direction in which >• 

 the error occurs, and the maximum i 

 extent of it ? J 



4. Would it be possible to eliminate the 



error by taking certain well-defined 

 precautions ? 



5. Which process of analyzing Phosphates 

 is in your opinion the most accurate ? 

 and how long does it require ? 



G. Which is the most rapid and con- "1 

 venient ? J 



Which gives the most constant results 1 

 in the hands of different manipulators ? J 



8. Do you know of any reliable process 

 for the estimation of the so-called "Ee 



n 



, will yoi 

 give details of the method ? 



duoed Phosphates?" If so, will you | 



0. Do you think it desirable that Chemists ] 

 should be called on to state the com- [• 

 mercial value of a manure ? J 



10. What in your opinion are the relative ^ 

 values which should be attached to 

 Phosphoric Acid existing in the fol- 

 lowing forms, taking free anhydrous 

 Phosphoric Acid as 100 ? 

 A. — As Acid (soluble) IPhosphate of 



Calcium. 

 B. — As insoluble Phosphate of Cal- 

 cium. 

 C.—As " Keduced " Phosphate of Cal- 

 cium. 

 D. — As Phosphate of Aluminium. 

 E. — As Phosphate of Iron. J 



