T H E J O 1 7 R S a 1 L O F IA\-D17STRI.4L A S D E - V G I S E E R I S G C H E M I S T R Y
Map, 191j
sures higher t h a n ordinary on t h e explosibility of methane-air mixtures. T h e first experiments were made with pressures u p t o five atmospheres, b y raising t h e level bottle of t h e a p p a r a t u s high enough t o p u t the gas under this pressure. It was found t h a t increased pressure u p t o five atmospheres h a d no effect in changing t h e low limit of complete propagation. I n other words, t h e value, a b o u t j . j o per cent methane. is t r u e a t five atmospheres pressure. S U 11 MIA RY
When t h e initial temperature of methane air mixtures is j o o " C., t h e low limit of complete propagation of flame of t h e mixtures is between 3 ;j a n d 4 . 0 0 per cent methane. As t h e initial temperature is lowered from j o o o C., t h e low limit is raised until a t ordinary temperatures i t is about j . j per cent methane. Differences in t h e initial temperature of as much as 200' C . higher, shift t h e low limit only from 5 . j o per cent t o between 4.98 a n d j . I j per cent methane. T h e results are i m p o r t a n t in t h a t t h e y show t h a t pressure a n d temperature conditions m a y vary over rather a wide range without affecting t h e explosibility of methane-air mixturef . Inconsistent results t h a t have been obtained i n t h e laboratory b y different investigators on t h e limits of inflammation of methaneair mixtures cannot be explained on t h e basis of slight variations in temperatures a n d pressures. T h e y are better charged t o t h e nature of t h e source of ignition, method of ignition, size a n d shape of t h e containing vessel, a n d in some cases, inaccuracies in mixing a n d analyzing the gases. Since t h e low limit of complete inflammation for methane-air mixtures is not changed at pressures as great as five atmospheres, i t can be s t a t e d t h a t even i n t h e deepest coal mines t h e low limit is not altered from t h e limit a t ordinary temperatures. CHEMICAL LABORATORY, BUREAUO F hlINES
PITTSBWRGH
THE VARIATION IN COMPOSITION OF NATURAL GAS FROM DIFFERENT SANDS IN THE SAME FIELD' , B y G A. BWRRELLAND G. G. OBERFELL Received December 15, 1914
I n working on t h e composition of n a t u r a l gases from different p a r t s of t h e country, t h e authors have found t h a t n a t u r a l gases from different sands in t h e same field m a y differ appreciably in composition. Invariably t h e gas f r o m t h e shallower sand has contained less of t h e heavier paraffin hydrocarbons t h a n t h a t from t h e deeper sands. T h e most striking variation yet encountered has h a d t o d o with n a t u r a l gases from t w o different sands in a gas field near Trafford C i t y , Westmoreland C o u n t y , P a . a n d not far from Pittsburgh. T h e compositions of these gases follow: GAS F R O M Murraysville sand Elizabeth sand Depth of s a n d . . . 1700 f t . 2295 f t . Rock pressure. .. . . 190 lbs. per sq. in. 1000 lbs. per sq. in. CONSTITUENTS C o t CHI h-2 COX CHI CzHe Percentages .... . . Trace 9 8 . 8 1 . 2 Trace 94.0 5.2 '
.
.
Nt 0.8
It will be noted t h a t f r o m t h e shallow s a n d there was collected a sample of almost pure methane, while in t h e deeper sand there is contained in addition t o 1
Published by permission of the Director of the Bureau of Mines.
419
methane a n appreciable proportion of t h e higher members of t h e paraffin series of hydrocarbons. If one were t o assume a common source of origin for t h e natural gases in t h e t w o sands, t h e n b y some process of separation t h e gas in t h e upper sand has been freed of i t s ethane a n d higher paraffins. I t should be added t h a t t h e paraffins were analyzed by burning t h e m in oxygen. not b y fractional distillation; hence in t h e case of t h e gas from t h e deep sand, only t h e t w o predominating paraffins are shown. Undoubtedly small proportions of propane, t h e butanes, etc., were also present, as in t h e case of other natural gases containing methane a n d ethane. CHEMICAL LABORATORY, BCREACO F MIXES PITTSBURGH
A SIMPLIFIED FERROUS SULFATE METHOD FOR THE
DETERMINATION OF VANADIUM IN STEEL By GEORGET. DOUGHERTY Received October 17, 1914
I n t h e application of Johnson's' or similar methods for t h e determination of vanadium in steel, considerable difficulty is often experienced in producing a colorless or "old rose" shade with ferrous sulfate in t h e solution containing a n excess of permanganate after t h e ppeliminary oxidation of t h e 1-anadium. T o obviate this difficulty t h e following method has been developed. i n which this oxidation of t h e vanadium is effected by a sufficient q u a n t i t y of nitric acid alone or with a m monium persulfate. METHOD-Treat 2 t o 1 g. of t h e drillings in a j o o cc. Erlenmeyer flask, with 6 0 cc. of water a n d I O cc. concentrated sulfuric acid. After heating t h e solution nearly t o boiling. until t h e reaction is complete, a d d 40 cc. of nitric acid (sp. gr. 1.20) a n d boil thoroughly for I O minutes t o oxidize t h e iron a n d vanadium a n d t o expel t h e last traces of nitrous fumes. Cool t h e solution. a d d 6 0 cc. of cold sulfuric acid (I : z ) a n d dilute in a 600 cc. beaker t o 4 j o cc. Add 3 cc. of a freshly prepared I per cent solution of potassium ferricyanide, a n d t i t r a t e rather rapidly, with constant stirring, with 0.05 N ferrous ammonium sulfate, t o t h e appearance of t h e first d a r k blue color. T h e e n d point can best be observed b y looking through t h e side of t h e beaker t o w a r d t h e b o t t o m of t h e beaker placed directly before a window. Deduction of a blank of 0.4 cc. of t h e ferrous solution has been found necessary, a n d is independent of t h e weight of t h e sample, t h e presence of chromium, a n d of t h e carbon content u p t o 0.j per cent C . F o r steels with over 0.50 per cent C, t h e blanks are higher; a n d , moreover! with 4 g. samples of such steels, t h e e n d point is rendered indistinct b y a turbidity which appears toward t h e end of t h e titration. This difficulty m a y be avoided b y adding t o t h e solution immediately after t h e boiling with nitric acid as above, 60 CC. of I : P sulfuric acid a n d j t o 8 g. of ammonium persulfate (which i n t h e absence of silver nitrate will not oxidize t h e C r a n d M n ) , a n d continuing t o boil for I j minutes, so t h a t all nitrous oxides a n d hydrogen peroxide are expelled. (Before this second boiling, wash down with h o t water loose specks of t h e per1
C. M. Johnson, "Analysis of Special Steels."
