176 LETTER-FILES OF S. W. JOHNSON 



Stoeckhardt "s young man analyzed, and that Wolff, v. Gohren, 

 Kiilin, etc., quote as a "mittel. " Haven't the figures here in 

 my Trumbull St. attic, but will publish them by and by. 



I have done a heavy amount of work on P2O5 estimations 

 during two or three years past, mostly with negative results, 

 don't know as I shall ever get time to write up. Before Carius 

 published, I had satisfied myself that pure H^O and common 

 air yield NH^NO., at temperature from 20° to 100° Centi- 

 grade. I never did believe half of Schonbein's facts, and now 

 that Carius finds that ozone doesn't oxidize nitrogen, I wish 

 old Schonbein were alive again to hear it ! As to PoOg, I find 

 that Otto's use of T to keep up FegOs and AI0O3 when you 

 ppt. PoOg with ]\Ig solution is simply perfect, if you use 

 enough T, enough to give a greenish-yellow solution and 5 to 

 10 grams of T doesn't impair the result seriously, but if you 

 use too little T and have a reddish-yellow solution, you have 

 an imperfect separation of P2O5. Ci is of no use, Church 

 Yille, and De Vill to the contrary. 



Invpried rose "of 



per/oraiee/ii'n v/iin 



Jlai /ilier onl/oHoni 



Thought I had a method for coming it over the superphos- 

 phates in one cowp, viz., to aqueous or acid solution, with Fe ; 

 Al, CaSO^, &c. &c, add q. s. (NHJoT, MgSO^, NH.Cl and 

 NH3 — filter on inverted ' ' rose " of " perforated tin ' ' with flat 

 filter on bottom, wash, without transferring ppt. moisten with 



