382 Phelps — Combustion of Organic Substances, etc. 



below, 20 cm3 of purified sulphuric acid were used in the carbon 

 determination and 35 cm3 of hydrochloric acid (sp. gr. 1/2) in 

 the chromic acid determination. The ammonium oxalate used 

 was the pure crystallized salt ; the phthalic acid was recrystal- 

 lized from its water solution and dried for a short time over 

 sulphuric acid ; the cane sugar was selected crystals of rock 

 candy, recrystallized from dilute alcoholic solution and dried 

 for a long time over sulphuric acid ; the paper was ashless 

 filter paper, dried to a constant weight over sulphuric acid ; 

 the tartar emetic was recrystallized from water solution and 

 air dried ; the barium formate was prepared by treating formic 

 acid with an excess of pure barium carbonate, filtering hot and 

 allowing the product to crystallize. 



Table VII. 









Error 





Oxygen 



Error 



Substance 



G0 2 



on K 2 Cr 2 7 As 2 3 As 2 3 Oxygen 



required 



on 





taken. 



found. 



C0 2 . taken, taken, found. 



used, by theory 



Oxygen. 





grm. 



grm. 



grm. grm. grm. grm. 



grm. 



grm. 



grm. 









Analysis of ammonium oxalate. 







1. 



1-0122 



0-6265 



0-0001— 2-0009 1-3002 O'OOOO 



0-1160 



0-1139 



0-0021 + 



2. 



1-0019 



0-6212 



0-0010+ 20002 1-3517 0440 

 Analysis of phthalic acid 



01147 



0-1128 



0-0019 + 



1. 



0-1002 



0-2138 



0-0014+ 2-0012 1-2004 0-0814 



0-1456 



0-1448 



0-0008 + 



2. 



0-1093 



02324 



00007+ 2-0000 1-1031 0-0634 

 Analysis of cane sugar. 



0-1582 



0-1580 



0-0002 + 



1. 



0-2025 



0-3117 



0-0008- 3-0000 1-7002 00796 



0-2275 



0-2273 



0-0002 + 



2. 



0-4012 



0-6166 



0-0024- 5-0000 23022 0*0366 

 Analysis of paper. 



0-4495 



0-4502 



0-0007 — 



1. 



0-3034 



04932 



00010- 35015 1-4017 0-0879 



0-3589 



0-3598 



0-0005- 



2. 



0-4523 



0-7334 



0-0033- 5-0035 1-8000 00710 

 Analysis of tartar emetic 



5368 



0-5358 



0-0010 + 



1. 



0-5057 



0-2671 



0-C009- 2-5018 1-7000 0-0766 



0-1459 



0-1462 



0-0003- 



2. 



1-0099 



0-5321 



0-0030- 3-5003 1-7520 0'0198 



0-2911 



0-2919 



0-0008- 









Analysis of barium formate. 







1. 



1-0079 



03906 



0-0006+ 3-0026 22002 0-0496 



0-1423 



0-1422 



0-0001 + 



2. 



1-5014 



0-5814 



0-0005+ 3-0010 1-8080 0890 



0-2118 



0-2118 



0-0000 ± 



From these results, it will be seen that the process works 

 with accuracy upon a great variety of organic substances. It 

 was found impossible, however, to determine the elements in 

 bodies which are at the same time volatile and hard to oxidize ; 

 for instance, ether oxidizes easily to acetic acid but difficultly 

 beyond that stage ; although the liquid acid is oxidized vigor- 

 ously by chromic and sulphuric acids, the gaseous acid is hardly 

 attacked at the temperature used ; naphthaline was also found 

 to be volatilized, and hence not attacked, to such an extent as 

 to render its determination by this process valueless. 



In conclusion, the author wishes to express his thanks to 

 Prof. F. A. Gooch for many helpful suggestions. 



