CHEMISTRY. 



195 



was substituted for it. The metliod used was as follows: Place 0.5 

 gm. of substance iu a 1J.")0 cc. tiask with 20 cc. of sulphuric acid and 1 

 to 2 gm. of dry and pulverized pyroi)hosphate of soda. Incline the 

 flask slightly and heat gently at first until the evolution of fumes of 

 sulphuric acid has subsided and the i)yrophosi)hate has dissolved, 

 which geuerall}^ requires about 20 minutes, then gradually increase 

 the temperature until the acid boils. Continue the digestion until the 

 solution is limpid and but slightly colored. Cool, dilute with water, 

 remove to a liter flask, add a little litmus solution, and connect with a 

 condenser. Run in soda solution through a funnel until the blue color 

 just disappears on shaking, add 3 gm. of magnesia, dilute to 450 to 

 500 cc, and distill the ammonia in the usual way. This requires from 

 1| to 1^ hours. 



Comparative results by diflerent methods are shown in the following 

 table : 



Determinations of nitrogen hy different methods. 



Substance. 



Horn 



Meat 



Do 



Do 



Dried blood... 



Do 



Do 



Fish fertilizer 



Do 



Do 



Pigeon dung.. 



Do 



Oil cake 



Fertilizer 



Do 



Do 



Soda-lime 

 method. 



Per cent. 



13.00 



10.34 



8.65 



9.50 



11.40 



10.45 



11,20 



8. 05 



9.05 



10. 15 



6.95 



0.27 



5.25 



2. 15 



8.85 



1.90 



Kjeldahl 

 method, 



using 

 mercury. 



Per cent. 



13.00 



10.35 



8.65 



9.45 



11.35 



10.45 



11.15 



8.85 



9.90 



10.00 



G. 90 



6.27 



5.25 



1.95 



8.80 



1.90 



Sulphate of potash method. 



10 gm. 

 Decolor- 

 ized in 

 1 to 2 

 hours. 



Per cent. 



13.15 



10.41 



8.75 



9.30 



11.40 



10.55 



11.05 



8.95 



10.00 



10.00 



5 gm. 

 Decolor- 

 ized in 

 2 to 3 

 hours. 



Per cent. 



13.15 



10.45 



8.75 



9.40 



11.45 



10.55 



11.10 



9.00 



10.00 



10.00 



2gm. 

 Decolor- 

 ized in 

 2J to 3^ 

 hours. 



Per cent. 

 13.20 

 10.45 



8.80 



9.50 

 11.50 

 10.60 

 11.15 



9.05 

 10.00 

 10.10 



7.15 



5.25 

 2.15 



8.85 

 1.95 



1 gm. 

 Decolor- 

 ized In 

 3 to 4^ 

 hours. 



Per cent. 

 13.20 

 10.45 

 8.80 

 9.55 

 11.50 

 10. G5 

 11.20 

 9.00 

 10.00 

 10.15 



Sodium pyrophos- 

 phate method. 



2 gm. 

 Decolor- 

 ized in 

 I to 2 

 hours. 



Per cent. 

 13.20 

 10.40 



10.65 

 9.05 



10.15 

 7.18 

 6.30 

 5.30 

 2.20 

 8.90 

 1.95 



1 gm. 

 Decolor- 

 ized in 

 2Jto3 

 hours. 



Per cent. 

 13.20 

 10.45 



9.50 



'io.'eo 



"9.06 



10.10 

 7.20 

 6.30 

 5.25 

 2.15 

 8.90 

 1.95 



The determination of potash, C. Fabre {Compt. Rend., 122 {1896), 

 No.23,])p. 13Sl-looo).—T\ie method proposed is as follows: The potash 

 salts are evaporated on the water bath with a slight excess of j)latinic 

 chlorid, adding toward the end of the operation a few drops of aqua 

 regia to destroy ammonium compounds. The residue is taken up in a 

 few cubic centimeters of distilled water and the solution again evap- 

 orated to dryness. The residue is ground up in the evaporating dish 

 with a few cubic centimeters of 90 per cent alcohol, collected on a filter, 

 and washed, first with alcohol until the washings are colorless, then 

 with a small quantity of ether. The precipitate is dissolved on the 

 filter with boiling water and to the solution, warmed to about 60° C, 

 purified (washed in alcohol) magnesium powder is slowly added, a large 

 excess being a\7oided. The reaction which occurs is as follows: 2Mg+ 

 K2PtC]6=2KCl + 2MgCl2+rt. To prevent the formation of oxychlorid 

 of magnesium it is well to add a few drops of sulphuric acid at the end 



