T H E JOlYRIVAL OF I N D U S T R I A L A X D EiVGI-VEERIiVG CHE-TIISTRY.
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h u t the present paper has already been extended t o a point demanding a n apology on the part of the author. It should, however, be remembered t h a t the present a r t is comparatively new and the difficulties presented and finally overcome are numerous ; iuthermore, t h a t the practical solution of processes and apparatus suitable for producing this new article of commerce, anh,vdro?u tin tstmchlovid, follows from experiences gained through working under conimercial conditions to the extent of nearly five tons per day of '4 hours, and naturally cannot be adequately treated in a few paragraphs. For a more complete understanding of the nature of these difficulties and means developed for overcoming same, reference is respectfully made to the specifications in certain patents given in the foot-note. See U.
s. Patents
REFERENCES. S o s . 382,092, 8 7 2 , 2 0 5 , 872,092, 873,699,
S i . l , O V , 874,ioip 87 5,632, 87 7,243, 877,244, 877,24j, 8771-
246, 8 i 7 , 2 4 i r 877,248, 8i9,j96, 882,354,883,500, 885,391, 88j,j38, 897, j96, 901,266, 906,32 I , 877,261, 87 7 , 2 6 2 , 877,263. Also English Patent KO. 25,496, '07, together with the
same patents in Germany, France, Belgium and Austria. Also English Patent S o . 8,302, ' 0 8 , and the same patent in the corresponding countries in addition to Italy, Switzerland and Japan. __--
THE DETERMINATION OF VOLATILE COMBUSTIBLE MATTER IN COKE AND ANTHRACITE.1 PORTER
\v,
SHI3fER.
Received M a y 12, 1909.
While the standard methodz for the determination of volatile combustible matter gives useful results on soft coals-for which class i t is primarily intended--the results are far too high when applied to coke and anthracite. This is due to oxidation of carbon and, to a lesser extent, to mechanical loss. The atmosphere within the crucible is oxidizing throughout the whole seven minutes' ignition in the case of coke and for perhaps the greater part of the time in the case of anthracite. I n the latter case, owing to the decrepitation of this coal when suddenly heated, the mechanical loss may be serious. A number of investigators, among them Neade and at ti^,^ have proposed making this determination in a n atmosphere of nitrogen or hydrogen. This, of course, necessitates the use of special apparatus and requires a good deal of time and attention. The results are trustworthy. 1 Read before the Lehigh Valley Section of the American Chemical Society, hfay 6 , 1909. J o u r . A m . Chem. Soc., 21, 1116.
3
I b i d . , 21, 1137.
Aug., 1909
For many years, until recently, the writer determined volatile matter on a five-gram sample of coke and anthracite, using a 25 cc. crucible. Before making the ignition a piece of wet asbestos paper was placed over the mouth of the crucible and the closely fitting cover was carefully and firmly pressed down upon it. This made a rather tight joint and the oxidation and mechanical loss were very much lowered. The larger weight of the sample (five grams as against one gram) also lessened the percentage of loss by oxidation. By a slight modification, however, the standard method may be successfully used. Instead of using a crucible with its cover, the writer now uses two platinum crucibles, without covers, of about 15 cc. capacity each. These are of such a size that, when the smaller one is placed inside the larger one, there will remain an open space a t the bottom of about one-quarter inch. The crucibles should be well formed and undented so as to make a close joint, the inner one taking the place of a cover. A . porcelain crucible may be used in place of the inner one, if of proper size and cylindrical in shape, but one of platinum is to be preferred, The method, in brief, is as follows: Ignite the combined crucibles, cool and weigh. Remove the upper one and place i t alongside of the other on the balance pan. Weigh into the lower crucible one gram of coke or anthracite. Press the smaller crucible securely down into the lower one and heat for three and a half minutes over the Bunsen and immediately follow this with three and a half minutes over the blast lamp. Simple ignition of seven minutes over the Bunsen, as in the standard method for soft coal, is not enough to drive off all the volatile matter from coke and anthracite. By this double crucible arrangement the interior air space is cut down to a minimum and the joint between the two crucibles is of such a character that very little, if any, air can enter during the ignition. Two more things may be done to rninimize still further any possible loss by oxidation. Ten drops of absolute alcohol may be placed on the coke and this may be burned off-in the process expelling the air--by gently and carefully warming the crucibles before beginning the seven minutes' ignition. I n most cases, however, this addition of alcohol causes no material difference in the results. A useful precaution to minimize mechanical loss, especially in the case of anthracite, is to work into the joint between the two crucibles a very little stiff starch or flour paste. A t the beginning of the
IVALKER AA-D IVHITMAN O X RAPID ALVALYSI.5 OF BABBITT IZIETAL. ignition this carbonizes instantly and serves to retain the decrepitated particles thrown off in the early part of the ignition. The paste is completely burned away some time before the end of the operation. I n certain cases the crucible containing the coke is more or less attacked, and i t is well, therefore, to use a small boat easily made of thin platinum foil, fitting closely into the larger crucible and high enough to contain the sample. A few of the results obtained in this investigation will suffice to show the difference between the two methods of ignition. -4 one-gram sample of coke lost in seven minutes’ ignition, as in the standard method, with crucible cover, 2.96 per cent. volatile matter. The same sample, when given another seven minutes’ ignition in the same way, lost 1 . 9 7 per cent. additional. Using the same Bunsen flame, a one-gram sample of the same coke, ignited for seven minutes in the double crucible, lost 1 . 2 0 per cent. and, on giving i t an additional seven minutes, the loss was only 0 . 1 2 per cent. To show that all the volatile matter is not driven off by the Bunsen flame alone, the following results, among many similar ones, are given. A one-gram sample of another coke yielded 1 . 5 1 per cent. volatile matter by seven minutes’ ignition over the Bunsen flame in the double crucible. The sample was again heated for three and one-half minutes over the blast lamp and sustained a further loss of 0 . 7 3 per cent. volatile matter. On igniting again for three and one-half minutes over the blast lamp there was no further loss. I t is not necessary to insist on the importance of a fairly accurate determination of volatile matter, for it is not only of value in itself but is essential to the correct determination of fixed carbon.
[COXTRIBUTION FROM THE CONTRACTS LABORATORY, BUREAUO F CHEMISTRY. PUBLISHED BY PERMISSION OF THE SECRETARY O F AGRICULTURE.]
RAPID ANALYSIS OF BABBITT METAL. By PERCY H . WALKER AND H. A. WHITMAN. Received May 21. 1909.
Methods for the analysis of alloys of lead, tin, antimony and copper, which are based upon the separation of lead and copper from antimony and tin by the use of alkaline sulphide solutions, are all exceedingly tedious, though with the necessary care, skill and patience, i t must be admitted that a method based upon this principle gives results
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of greater accuracy than any of the more rapid methods. This method is, however, so tedious that it can seldom be used in a commercial laboratory, and when i t is used the chances of loss are so great that frequently the whole analysis must be recomnienced after spending several days on the tedious separation. The more rapid methods which are often based upon the separation of antimony and tin by treatment of the alloy with nitric acid are open to the serious objection that one portion of the alloy is used for several determinations and the errors in separation appear again in the determination of the individual metals. It is highly desirable that we have a method using a separate portion of the alloy for each determination, and that the metal to be determined in each case be dissolved before it is determined. Except for the method of separating copper (and even here Fresenius’ gives a similar method of separating copper from nickel), there is no new method suggested in the scheme we present. The details of the various determinations have, however, been studied and sources of error in the determination of lead and copper are pointed out, so that by following the method as described and applying the proper correction as accurate results can be obtained as by the alkaline sulphide process in a far shorter time and with much less labor. THE METHOD. Cofi+er.--Weigh I gram of the alloy into a 2 5 0 cc. beaker, add 2 0 cc. hydrochloric acid and 5 cc. water, heat and complete solution by adding nitric acid in small amounts; with most alloys solution can be effected in a very few minutes and without adding more than I or 2 cc. of nitric acid. Evaporate off the acid on a steam bath. It is not necessary to carry to complete dryness, but practically all the acid should be driven off and the residue should be pasty. Add 2 5 cc. of a solution made of 2 0 0 grams tartaric acid, 260 grams of potassium hydroxide, the whole being made up to 500 cc. with water. Heat on the steam bath until solution is completed, add 2 5 cc. water, boil, add 2 5 cc. of a 0 . 2 per cent. invert sugar solution, boil for two minutes, filter through asbestos, wash the precipitate of Cu,O with water, dissolve in nitric acid, catching the copper solution in a zoo cc. flask, and determine copper by any good volumetric method. We have found that equally good results can be obtained by following Low’s iodide “Quantitative Analysis,”
Vol. 1, p. 684.
