I IO0
H . C. S H E R I f h N .
acid. The phosphoric acid was determi'ned in the resultant solution, and in three determiiiatioils the results \\-ere respectively 2.18, 2 . 2 2 , and 2.31 per cent. This shows that the phosphoric acid was readily taken into sblution by the action of nitrohydrochloric acid on the seed meal. but in such form that it could not be entirel! precipitated by ainmonium molybdate till after ignition and subsequent solution in nitric acid. \\-ark done b>- Hardin' indicates the presence of meta- ant1 pyrophosphoric acid in cottonseed-meal : but these forins o i phosphoric acid should be convertecl into orthophosphoric acid b y boiling with strong nitric acid. Possibly the phosphoric acid i n cottonseed-meal is in organic combination that is not broken up by boiling with strong nitroliytlrochloric acid and can only be set free by ignition or fusion. The cottonseed-meal \vas extracted jvith anhydrous ether, and the ether estract was fused with potassium hydrodixe and potassium nitrate and the sulphur and phosphorus determined. T h e extract contained 0.47 per cent. phosphorus pentoxide, probably contained in ether-soluble lecithins : most of the phosphorus in these compoiuitls is driven off by ignition and this nould account for some of the difference i n results bet\\-een the methods of fusion n i t h alkali and simple ignition. The sulphur obtainetl from the ether estract 11y the fusion method amounted to 0.30 per cent. of thc extract, or calculated to original substance. 0.03 per cent.
[COSTRIBUTION FRO31 T H E H.IT'E3IEYER
I,ABOR.%TORIES O F COLUIIBIA
L-SITERSITY, S o . 71.1
T H E DETERMINATION OF S U L P H U R , A N D PHOSPHORUS IN ORGANIC MATERIALS. ns
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c. S H E R M A S .
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T H E D E T E R l I I S . \ T I O S OF SULPHUR.
Is order to secure complete osidation of the sulphur of organic materials without loss through the formation of volatile compounds a great many modes of procedure have been described. \Yithout attempting an enumeration of these it may be said that nearly all of them fall under one of three general heads: 1
Bulletin 3 j U. S . Dept. of Agriculture. Division of C'lernistry. p. 50.
SULPHUR A N D PHOSPHORUS I N O R G A N I C MATERIALS. I IO1
of nitric acid in a sealed tube ; ( 2 ) heating in a combustion tube in a current of air, oxygen or some oxi( I ) oxidation by means
dizing vapor-the oxidation being sometimes completed by means of platinized asbestos ; ( 3 ) fusion with an alkali (sometimes with previous treatment with nitric acid), the oxidation being completed either by the addition of an oxidizing agent to the fusion or by treating the alkaline solution with chlorine or bromine. The first method is quite inconvenient for samples low in sulphur because only small amounts of material can be decomposed at a time and determinations are frequently lost through breaking of the tubes. The second method requires the fitting up of special apparatus and is not apt to be used unless many determinations are reqiiired. Hence some modification of the third general method is apt to be preferred and the most common is perhaps the fusion of the substance with sodium hydroxide with the addition of nitrate or peroxide to complete the oxidation. This method, if carefully carried out, can be made to yield very accurate results, a t least with ordinary materials, but it appears that equally accurate results can be more conveniently obtained by direct combustion in oxygen. Certhelot in 1892' proposed the use of the calorimetric bomb for the elementary analysis of organic substances and stated that on combustion with 2 j atmospheres of oxygen the sulphur, as well as the carbon and hydrogen, was completely oxidized, and in the presence of moisture remained entirely in the form of sulphuric acid. This method has been used to some extent, especially for the determination of sulphur in coals, and Hempel has described* a modification in which the combustion is accomplished in a large glass vessel with oxygen at ordinary pressure. i2s an additional precaution the gases from the bomb after the combustion may be made to pass through bromine water to which the rinsings of the combustion chamber may afterwards be added and the whole boiled to insure the oxidation of any sulphurous acid which may have been formed. This is considered unnecessary by Hempel and the following experiments show that the bromine was not needed with the samples here used : Dried meat, dried curd and white of egg were burned and the sulphur deter1 2
Compl. rend.. 114,317, 316. Zlschr. angew Chem. (1892). pp 303-39
I I02
11.
C. S H T < K l I . \ S
i-ii:ig bi-iniiitic w a t c r .
\..iiig
I)rie(l lean ineat. ....................... o.S11 Dried curt] ............................. o.61 I Ikitd white of e g g . . .......... ..... 1.406
water fii:Iy,
0.S16 0.609
1.410
Tlicsc tests seemed to slio\v conclusively that ior th the iiw o f I)romiiic \vas ciitirely unnecessary antl in tlic subsequait iise of this methotl we have carried it out as folio\vs : C'oiiipi*cs.sctl 0.rygcu JIethod.--h suitable w i o u n t o f sample is pressed iiito a pellet and buriietl in tlic I)oiiib-calol-imeterl i n the s m c iiiaiiiier as in the determination of heat of coml)ustion, iisiiig iron1 2 , to 30 atmospheres of osygcii. 1;). iiicaiis o f a coupling \\.it11 small bore the bomb is then coiinectetl \\.it11 a \vasli-l)ottle c'ont~iiiiiii~ \vater. antl the gas is allo\vctl to bubble through the \vatcr iintil the contents of the bomb reaches atmospheric 1)ressure. ivlici; it is opened and tliorouglilj. riiisctl \\-it11 ivatcl-. In t ~ r d c rt o Im7) tlmvn the \.oltiine. tlie water from the ivasli-bottle is iisctl f o r the tirst ritisiiig. .In!. ash fount1 i i i tlie combustiou capstulc is tlissol\ctl 1)). mcans of hytlrocliloric acitl ant1 tliis soliitioii atltled to the maiii solution. 'l'lic \vhole is thcn Iioiletl t l o\ vn t o the desired \ o l u i i i c . , filtcretl i f iiecessary. ant1 the siilphuric acitl tlcterniiiieti I)? i)i-ccipitation ivitli barium cliloritle. This mct1ii)tl has becii applietl to a ic\v sulphur coiiipoiiiitls prepai-cvl 11). stu(1ents iii the organic laborator)., selecting ~ 1 1 ~ 1ns 1 containe~ls1il1)hiir in an "unositlizetl" contlitioii in ortlei- to make the, t
