T H E JOUR,"\AL
2 58
OF I , V D C S T R I A L .4,VD E S G I h 7 E E R I A V GC H E J I I S T R Y .
I should use 2 cc. of strong solution diluted to 30 cc., partly because bullions are liable t o carry much more platinum than any ordinary ore, and partly because the volume of, the silver nitrate solution from parting the gold must necessarily be larger. If, however, i t is known t h a t minute amounts of platinum are present, it is still necessary to use sufficient hydrogen sulphide to give a silver bead large enough to handle comfortably. For this reason I seldom use less than the equivalent of I cc. of strong hydrogen sulphide solution. It may happen t h a t the final metal shows the yellow color of gold, due to the fact t h a t exceedingly fine float-gold passed over in decanting the solution of silver nitrate from the gold. In such a case the metal must be realloyed with silver and the treatment repeated. When the proportion of gold to silver in the metal being parted is so small t h a t the gold separates in a very finely divided state, it will often save trouble to filter the silver-nitrate solution, to separate any float-gold, before adding the hydrogen sulphide. This method has been used with the utmost satisfaction in determining very minute amounts of platinum in various silver-products directly. Much of our silver coinage, for instance, will show a few tenths of a milligram of platinum in I O O g. of coin. Recently I examined samples from two purchases of fine silver. Very large samples were dissolved in nitric acid. The acid in portions was poured upon the samples and allowed to act a t a gentle heat until exhausted. Finally, a small amount ,of residual silver was removed from the solution and dissolved in a small amount of fresh acid, the solution being then united with the main solution, and the whole evaporated nearly to dryness. I t was then diluted to about 2 5 0 cc. and j cc. of strong hydrogen sulphide solution diluted to 50 cc. was poured in with constant stirring. This operation concentrated the gold and platinum of the silver into a small amount of sulphide precipitate. This precipitate was filtered off, roasted, and cupelled. The resulting bead was parted in nitric acid, and the gold determined. The silver nitrate solution was treated with dilute hydrogen sulphide solution, equivalent t o about I cc. of strong solution, and the platinum parted from the silver b y strong sulphuric acid. These two samples yielded the following results : Silver taken. No. 1... . . . . . . . . . . . 2. . . . . . . . . . . . . .
Gram.
Gold found. Milligram.
122.32 125.47
0.28 0.12
Platinum found. .Milligram. 0.67 0.18
I n case we have a material containing a considerable amount of platinum, the well known fact t h a t platinum alloyed with silver is not entirely soluble in nitric acid must be considered. In such a case the gold from the first parting in nitric acid must be alloyed with silver and parted in nitric acid a second, or even a third time, before proceeding to precipitate the platinum from the parting solutions with hydrogen sulphide.
April,
1912
I t is also very satisfactory to use the general method of gathering gold in a precipitate of silver sulphide in determining minute quantities of gold in highgrade silver, such as t h a t produced by electrolytic refining. I t is comparatively easy to gather the gold from very large samples of silver, up to I O O g. or more, into a decigram of silver, and then part by nitric acid as usual. Probably this method of precipitating a noble metal in solution, or removing i t from suspension in a liquid, by adding hydrogen sulphide in the presence of silver in the solution, could be used t o advantage in determining gold in metallic copper and similar materials. LABORATORY, UNITEDSTATESMINT BUREAU, \VASHINGTON.D. C.
THE DETERMINATION OF MOISTURE IN COALS. By
E. H. ARCHIBALD AND J . N. LAWRENCE Received Feb. 7. 1912.
According t o the official method for the determination of moisture in coal, the sample should be heated for one hour, preferably in a double-walled toluene bath, a t a temperature of 104-7', the loss in weight of the sample being taken as the moisture. I t is of course recognized by many t h a t the result does not necessarily represent the true moisture, but the magnitude of the error t h a t may be made by following these directions does not seem t o be appreciated. The following experiments were undertaken for the purpose of comparing the quantity of moisture which might be found according t o the official method, with t h a t which may be taken as representing the true moisture and thus ascertaining the magnitude of the errors which might be caused b y oxidation of the coal, and evolution of gases a t different temperatures, and the retention of the moisture by certain coals, which, being very porous, hold the water very tenaciously. The work t h a t has been done upon occluded gases in coal has a direct bearing upon this problem. Obviously, the more gas given off during heating, other things being equal, the larger the error which will be made. That carbon dioxide, oxygen, methane, nitrogen, carbon monoxide and ethane are evolved from peats and coals when heated, has been shown by Websky,' VonMeyer,l tho mas,^ and a number of other investigators. Parr and Baker4 have shown t h a t when coal is first mined it evolves hydrocarbons, chiefly methane, quite rapidly; but after a period of four months scarcely any methane is given off. Their data also show t h a t carbon dioxide is evolved especially at a high temperature, and t h a t oxygen is continually absorbed. Porter and Ovitzs found t h a t some coals dried in the air a t 115' C. lose appreciable amounts of carbon J . firakt. C k m , 8'2, 7 6 (1864). I b z d . , 5, 144 (1872). 3 J . Chem. Sac.. 13, 793 (1875). 4 Uniu. of Ilt. Eng. Ex*. Statron. Bzlll. 32. 5 J . A m . Chem. Sac., 30, 1486 (1908). 1
2
April, I 9 I 2
T H E JO UR*YV,4LOF I-YD U S T R I A L A X U E.VGIL\TEERI-VG C H E - U I S T R Y .
dioxide, and a great many take up oxygen. These authors have also shoxn that the coal absorbs oxygen without forming carbon dioxide. E . E. SomerrneierI has called attention t o the fact t h a t lignitic coals give up their moisture more slowly than harder coals. Kent’ has suggested heating the coal in an atmosphere of nitrogen, absorbing the moisture given off by means of calcium chloride, and determining the increase in weight of this drying agent, which should represent the true moisture. N. W. Lord3 notes that when finely ground samples of Illinois and Indiana coals were heated for different lengths of time, in different amounts, and under different conditions, practically all the moisture was expelled in the first thirty minutes; further that the change in weight represented not only the loss of moisture, but included any change due t o oxidation, or other cause. The recent work done by Porter and Ovit24 dealing with the subject in hand is most interesting. They were especially concerned with the volatile matter evolved from the coal a t temperatures between 400 O and T I O O ~ . They also conducted a series of experiments for the purpose of weighing directly the moisture drii-en off from the coal a t I o j o when heated in a current of dry air or in nitrogen. The gaseous products were as far a s possible collected and weighed. Their results show that a slight amount of carbon dioxide is produced by drying the Illinois and Wyoming coals a t IO^", but only slight traces of hydrocarbons or carbon monoxide. Their experiments further showed that oxidation of the coal occurred t o the extent of 0 . 4 - 0 . j , the amount of moisture obtained by absorptions in calcium chloride being greater, in almost every case, than the moisture determined by the official method. The particular purpose of our work was to show t h e effects of heating the coal a t different temperatures, for different lengths of time. and the extent t o which a soft coal must be heated in order to expel the moisture. As will be shown below, the greatest ,error made in the determination of the moisture, b y the official method, is likely to be due, not t o .oxidation or evolution of gases, but t o the different rates a t which moisture is expelled from different coals. In the first set of experiments the coal was placed in a tube and heated in a stream of air free from moisture and carbon dioxide. After passing over the coal, this stream of air m-as led t o tubes containing anhydrous calcium chloride. The attempt was made to determine the amount of hydrocarbons given off, but this was not entirely successful. We can say, however, that the amount is exceedingly small below 110’; there seemed to be appreciable amounts a t I 2 0 ”. After heating for an hour, or two hours, the tube containing the coal was weighed, giving the change 1J.
A m . Chem. SOC., 28, 1630. “Steam Boiler Economy,” by Wm. Kent, p. 351. a U.S . Geol. S u m q Bull. 323, p. 18. 1..4m. Clcem. Soc., SO, 1185 (1908).
2
259
in weight of the coal. Also, the calcium chloride tube was weighed giving the moisture driven out of the coal. The difference between the latter value and the gain or loss in the weight of the coal tube should give the value of the change due to oxidation, evolution of gases and such causes. If gas mas evolved along with the expelled n-ater and some constituent of the coal oxidized a t the same time, the change in weight will be negative or positive as the first two effects or the latter are the greater. I n making the weighings, glass tares were used, of very nearly the same volume and surface area, and containing the same amount of substance as the tubes t o be weighed. The i~eiglits were carefully compared among themselves, and all corrections applied. The balance used was a long arm Recker which gave very constant results. Blank tests were run frequently in order to assure ourselves that the air or nitrogen used was free from moisture, carbon dioxide, oxygen or any harmful irnpurity. These tests always gave very satisfactory results. The experimental work may be classified as follows: ( I ) The experiments with bituminous coal heated in a current of air. ( 2 ) The experiments with bituminous coal heated in a current of nitrogen. ( 3 ) The experiments with anthracite heated in a current of air. (4) The experiments with anthracite heated in a current of nitrogen. In the case of the first set of experiments the coal was heated a t four different temperatures, viz., 7 j ” , r o o ’, I I O ’, and 1 2 0 ” starting with a fresh sample of coal for each temperature. Each sample mas heated one hour. then weighed, heated two hours and again weighed; while in the case of a few samples the heating was continued for two hours and then for one hour. At each of these intervals the change in weight of the coal and the true moisture given off was determined, as well as the unsaturated hydrocarbons evolved, if any. The data obtained are shown in Table I , expressed as percentages of the original weight of the coal. A gain in weight is indicated by the letter G. A loss in weight by L. These letters are inserted only when the result is different from t h a t indicated by the heading of the column. The results show that a t 7 j ” the loss in weight of the coal corresponds very closely to the moisture expelled from the coal: that an appreciable amount of moisture remained in the coal after the first hour of heating ; t h a t practically no unsaturated hydrocarbons were detected. At I O O O the moisture weighed was 0 , 1 9 7greater ~ than the loss in weight of the coal during the first hour. The coal gained instead of losing in weight during the second and third hours. This shoxs considerable oxidation as i t is enough to cause not only this increase in weight but to make up for the loss due to the evolution of any gases, which must have
T H E J O U R X A L OF I - V D U S T R I A L A X D ESGI*\-EERI-YG C H E J I I S T R Y - .
260
TABLEI. Unsat. hydrocarbons.
Loss in w-eight.
---
v1
Y
4
&
8 21
F,
aL
*
n
3
E
"4
a : :u
"b %&
.... ....
750 1.46 1.56 1.46
0.17 0.08 0.20
. . . . . . . . .... , .. , , ., . ....
0.12
1.60
1.49
0.15
1.64
1.66 1.55 1.67
G 0.02 G 0.05 G 0.05
....
....
100 0. 1.84 1.74 1.89
Aver.
1.63
G 0.04
1.59
1.82
1 2 3
1.65 1.53 1.65
G 0.09 G0.05 G 0.09
....
.... ....
Aver.
1.68
G 0.08
0.14 0.09 0.12
1.48
1 2 3
1.43 1.56 1.45
Arer. 1 2 3
1 2 3
Aver.
__
_-
__
_-
1 .75 1.72 1. i o
G 0.16 G 0.16 G 0.06
1.72
G0.13
--
-
....
-
........
....
....
....
.., . .,,. .... . . . . . . . . . . . . .... 0.07 . . . . . . . . .... -_ 0.10 1.92 . . . . .... 0.14
1100. 1.89 1.84 1.85
0.12 0.04 0.13
........
1.60
1.86
0.10
1.96
....
1200. 2.01 1.98
.... .... 1.59
0.22 0.19 0.19
1.87 ___
__
1.95
0.20
., .. .,,. ....
....
.... 2.15
,,, ,
.,.,
.... 0.09 0.09 0.04
0.07
April. 1912
ture as usually carried out, a considerable amount of moisture is left in the coal-at least 107;of the total moisture. If however the temperature is raised until this moisture is expelled, an appreciable amount of hydrocarbons in addition t o other gases will be driven off. Oxidation of some constituents of the coal takes place causing an increase in weight, which may be estimated a t about 0 . 8 0 7 , of the weight of the coal. We pass now t o the results obtained by heating the coal in a current of dry nitrogen. The nitrogen was prepared by passing air through ammonia water and then over heated copper. The results are tabulated as in the previous experiments. Loss in weight
TABLE11. Moisture weighed.
3;
m u
-
.-
Unsatd. hydrocarbons.
....
....
m u
....
.... 0.22 0.07 0.22 0.17
taken place t o some extent. Our method failed t o detect any unsaturated hydrocarbons. At I I O O the moisture weighed was 0.18% greater than the loss in weight of the coal. The gain in weight of the coal during the second and third hours is greater than a t 100' showing more oxidation, Another point worth noting is t h a t an appreciable amount of the moisture remains in the coal after the first hour's heating a t this temperature. The results at 1 2 0 ' show the moisture weighed t o be 0 . 2 3 7 ~greater than the loss in weight of the coal during t h e first hour. The oxidation during the second and third hours is appreciably more than for 100' at this temperature, and we have an appreciable amount of hydrocarbons evolved, b u t this is much more marked during the second and third hours. The amount of moisture given off during the second of and. third hours is considerable, being about 107~ the total moisture. If we wish to obtain some idea of the oxidation we must add to the difference between the moisture weighed and the loss in weight of the coal ( 0 . 5 6 7 ~the ) weight of unsaturated hydrocarbons found ( 0 . 1 7 7 ~ ) giving 0 . 7 3 % of the weight of the coal, a value which must be low, as we know other gases, as well as hydrocarbons, are given off. The results obtained b y heating the coal for the fourth and fifth hours, and again for the sixth, may be briefly summarized. The coal tube continues t o gain in weight, but the gain is much less than for the second and third hours. A small amount of hydrocarbons appears t o be given off a t 110". The moisture weighed is almost negligible even at 75'. All t h a t can be driven off at this temperature disappears during the first three hours. I t would appear therefore from these experiments with the soft coal that in the determination of mois-
4
R
:+
Pa 1 2 3
1.63 1.58 1.61
__
0.13 0.08 0.10
....
....
....
I
750. 1.40 1.44 1.42
0.06
..,.
0.20 0.18
.... ....
0.15
1s i
0.18 0.06 0.14
.... .... ....
-- --
Aver.
1.61
0.10
1.71
1 2 3
1.93 1.89 1.87
0.01 0.08 0.03
....
....
1.42 1000. 1.54 1.76 1.74
1.90
0.04
1.94
1.75
0.13
1.88
0.04 0.14 0.09
.... ....
Aver.
__
_-
....
--
1.99 1.87 1.92
G0.05 G0.03
--
.... -_
....
Aver.
1.93
G0.03
1.90
1.83
0.09
1.92
1 2 3
1.94 1.93 1.89
GO.O1 G0.03 GO.O1
.... .... ....
1200. 1.90 1.90 1.84
0.23 0.03 0.09
....
.... ....
1.92
G0.02
1.90
1.88
0.12
2.00
Aver.
_ _ _ _
....
....
_-
__
....... ........ ......
.......
. . . . . . .
~
1100. 1.84 1.82 1.84
1 2 3
........
9.
-
--
....
. . . . . . . . ........
. . . . . . .
0.10 0.10 0.00 _
0.07
.
0.36 0.22 0.03 -
'0.20
At 7 5 " the loss in weight of the coal was 0 . 1 4 7 ~ greater than the moisture weighed. A separate test made showed t h a t 0 . 0 8 % of carbon dixoide was evolved from this coal when heated. The results for 100' show t h a t the loss in weight of the coal during the first hour's heating was greater by 0 . I j 70than the moisture q-eighed. During the second and third hours' heating, however, the moisture weighed is greater then the loss in weight of the coal. This suggests the synthesis of some water from the hydrogen and oxygen in the coal. An appreciable amount of moisture is left in the coal after the first hour's heating. The results for 110' show the same variations as those for 100'. The moisture weighed is still less than the loss in weight of the coal, b u t the difference is now very small. At 1 2 0 " the total moisture weighed for three hours is slightly greater than the loss in weight of the coal. Doubtless an appreciable amount of gas must have been driven off; in fact the amount of heavy hydrocarbons is large enough t o be detected. Oxidation must have taken
April.
1912
THE.JOL7RAY.iL OF I - Y D C S T R I a 4 L A-I‘D ESGI.\-EERI-\TG
place t o a considerable extent. Water is still retained after a n hour of heating. If we assume t h a t the difference between the loss in weight of the coal when heated in nitrogen, and when heated in air, represents the oxidation, we can express the oxidation for the first hour in percentage values of the moisture, as follows: TABLE111. .4t At At At
750... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 100°... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1100. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 120’. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Per cent 8.72 14.84 13.44 10.26
The moisture in the bituminous coal was also determined a t the different temperatures in the official way, c i z . , b y heating one-gram samples in platinum crucibles for one hour. The results follow:
CHEXISTRY.
261
The carbon dioxide was determined for all the following experiments by absorbing the gas in potassium hydroxide solution. The further determination of the hydrocarbons was not attempted. As heretofore the results are percentage values of the original weight of coal. Tt is noted t h a t in the case of both coals the moisture weighed is greater than the loss in weight of the coal. The water is much more easily expelled from the anthracite coal, as i t is almost entirely driven off during the first hour of heating, while with the soft coal this was not the case. The next series of results was obtained b y heating t h e anthracite coal in an atmosphere of nitrogen. TABLEVI.
XI oisture
Loss in weight.
weighed.
7 -
TABLE IV.
I !
-4.
..
JIoisture, oflicial method. Total “moisture weighed” from Table I. Per cent. Per cent. I .oi 1,64 1.01 1.92 1.39 1 .96 1.29 2.15
--7
1-0,I.
Temp. 75 1000
S o . 11.
Per cent. 1.12 0 95 1.32 1.25
1100
1200
The true moisture in the coal is therefore greater than the moisture found b y the official method b y 407, ut’ the total moisture. I t appears from Tables 1-11- t h a t the moisture determination, as usually carried out, is in error from several causes: firsfly, as shown in Table 111, the value is too small b y r4C;- of the moisture, due t o an increase in \\-eight of the coal, caused probably by oxidation, which is far from being balanced b y the loss of occluded gases; and secondly, due t o the water t h a t still remains in the coal, which, considering Table IV, amounts t o about 2 6 % of the total moisture; the t w o errors combined amount t o 407, of the true moisture. We now come t o the experiments with the anthracite coal. I n the first place, we will consider the results obtained b y heating the coal in dry air. TABLEV
XI oisture
Carbon dioxide.
weighed.
Loss in weight.
75O C. 1
2 3
2.77 2.ii 2.74
...
0 02 0.01 0 01
....
2.77 1000
1
0 03 0.04 0 10
2.53
....
....
2 3
2.81 2.76 2.86
1 2 3
2.85 2.83 2.83
0.05 0.06 0.00
2.31 2.51 2.35
000 000 0.00
2.39
2.64 2.61 2.64
..,.
....
.... 2.47
c
. . . ....
2.84 2.77 2.79
2 3
....
2.48 2.41 2.45
....
....
1100 c. 1
.
.
....
....
2.81
.... . ., . ....
.... ....
1200 c. 2.54 2.45 2.53
2.84
....
....
....
2.62
....
....
.... ....
.... 2.51
The moisture weighed is appreciably less than the loss in weight of the coal. The difference is about 0.317,, while the carbon dioxide given off according . dift o the previous experiments was 0 .~ 3 7 ~The ference between these values, or 0.08Yc,represents roughly the unidentified gases. -4s was the case when the coal was heated in air, practically all the moisture is driven off during the first hour of heating. The amount of this moisture is almost the same for 7 5 ’ as for 120’. The analysis of the anthracite according t o the official method gave the following results: TABLEVII.
2.60 2.57
1 2
0.07
....
0.07
2.65
2.60 2.67
0.03
....
2
0.03
2.67
1 2
2.64 2.63
0.04 0.03
2.67
1
1 2
*
2.63 2.64
0.07 0.10
.... 2.72
....
0.16 0.14
none 0.07
....
0.15 0.18
0.07 none
..,.
0.16 0.26
none
2.62 2.70
0.22 0.19
2.86
2.64 2.63
0 31 0.13
2.86
2.73 G 0.11 . , . . 2.62 2.73 G 0.06 2.65 2.66 Tare was broken during the run.
0.11 0.05
2.72
....
0.23 none Sodetermination.*
0.11
Moisture by official method. ,--__A__-
Temp. 75 ,” 100 1100 1200
No. I.
Per cent. 2.37 2.30 2.39 2.40
No. 11. Per cent. 2.40 2.37 2 42 2 40
Total “moisture weighed” from Table V. Per cent. 2.72 2.87 2.88 2.72
The moisture as found b y the official method is less than the moisture here only from 1jy0 t o 20% weighed. The bituminous coal and the anthracite were both
262
T H E J O U R i V A L OF I ! V D U S T R I A L AND Eh’GINEERIiYG C H E M I S T R Y .
analyzed for iron, sulfur, volatile matter and ash. The results follow: TABLEVIII. Bituminous coal.
-
Anthracite.
-_L__,
Exp. I. Per cent.
Constituent. ’ Iron . . . . . . . . . . . . . . 0.65 Sulfur. . . . . . . . . . . . 1 . 0 2 Vol. matter.. 32.49 A s h . . . . . . . . . . . . . . 6.83
......
,
-
Exp. 11. Exp. I. Exp. 11. Per cent. Per cent. Per cent. 0.55 1.07 31.80 6.74
0.48 1.15 5.77 8.37
0.58 1.18 6.13 8.34
We see from these experiments t h a t the greater oxidation in the case of soft coal could scarcely be due to the greater amounts of iron and sulfur present, as these constituents are present to almost an equal amount in the two cases. Rather, the greater oxidation must be due to the fact t h a t the moisture is not so rapidly expelled from the soft coal. The curves shown in Figs. A and B serve to indicate very clearly the general character of the results. The temperatures are plotted as abscissae and the per cent. of moisture as ordinates. The curves of Fig. A represent the results for the bituminous coal, those of Fig. B the results for the anthracite. The total decrease in weight of the coal during the first three hours, which is shown in curve I of Fig. A is practi-
1912
the coal when heated in nitrogen, but this is not much greater for I Z O O than for 75’. Curve IV showing the moisture weighed a t the different temperatures is more difficult t o draw than the others as the results are not as regular. Obviously the result for 100’ is worthless. However, for the sake of completeness the points are indicated. The above considerations show that the errors made in the determination of moisture by the official method are much more serious in the case of bituminous coal than for anthracite. The determination being of little value in the former case, as a t present carried out, we suggest t h a t for this class of coals the method be modified, and t h a t the coals be heated in a current of dry air a t a temperature of a t least I I O O . the moisture given off being weighed directly after absorbing it by anhydrous granular calcium chloride. The results for one coal would then be comparable with those of another while a t present this is not the case. S U M M A R Y. 1t7e may briefly summarize our results as follows: ( I ) K h e n the determination of moisture in coals is carried out according to the official method, the result is much lower than it should be, the error
?SO?
7 9
cally the same for all the different temperatures, the curve being practically a straight line. Curve I1 shows the gradual increase in moisture given off b y %he coal as the temperature rises. Here too we have practically a straight line. Curve 111 represents the variation in the weight of the bituminous coal when heated for three hours a t the different temperatures, in nitrogen. For temperatures above I O O O the weight is constant. This curve lies throughout its whole length far above Curve I, showing the effect of oxidation when the coal is heated in air. The relation of the amount of moisture given off to the temperature when the coal is heated in nitrogen is set forth by Curve IV. The upper portion of the curve lies a little below Curve 11. This could be accounted for by assuming the synthesis of a small amount of water from the oxygen of the air and hydrogen present in the coal. The curves for the anthracite (Fig. B) resemble in some respects those for the bituminous coal. Curve I , showing the relationship between the change in weight of the coal and the temperature a t which i t is heated (in a current of air), is a straight line, as in the case of the soft coal. The total moisture given off by the coal when heated in air shows a maximum a t about 105’ (Curve 11). From Curve I11 we see t h a t there is a continual loss in weight of
April,
1 1 ’ ’
!
I
’
I
’
~
!q-LlIl 100
Fy,B
110 O
1 1 1 I /zo
amounting in the case of some bituminous coals t o 4 0 7 ~of the true moisture. ( 2 ) The oxidation of iron or sulfur or both, and the non-expulsion of a considerable part of the water which probably accounts for the largest errors here involved, are much greater in the case of bituminous coal than with anthracite: due on the one hand t o the moisture remaining in contact with the coal a t a high temperature for a much longer time, and further to the more porous nature of the softer coal. (3) It was suggested that for bituminous coals the method be modified and t h a t the coal be heated in a current of dry air a t a temperature of a t least IIO’, the moisture given off being weighed directly, after absorbing i t in anhydrous calcium chloride. CHEMICAL LABORATORY, SYRACUSE UNIVERSITY.
A METHOD FOR THE UTILIZATION O F LEAD FURNACE FUME. B y L. S. HUGHES. Received Dec. 18, 1911.
A large item of expense in the operation of lead smelting plants is the treatment of furnace fume. Where the so-called “open-hearth” furnaces are employed this by-product frequently amounts t o more than twenty per cent. of the total ore charge and
