N O T E S A N D CORRESPONDENCE. pump stopped. As soon as the vacuum is broken, 'the still drain should be opened and the residue allowed to drain into the foots tank, in which there should always be a few inches of liquid, and this should be mixed with the foots t o keep them from hardening. The still should be washed out with hot sweetwater. The hot sweetwater is first pumped into a perforated pipe in the top of the still having the drain valve open. The drain is closed later a n d . t h e still filled with sweetwater which is boiled with open steam. This operation to be repeated till still is clean. If chemically pure glycerine is to be made, the first distillate should have a gravity of about zgo Be. at 60' F. When the still is shut down, if sufficient steam has been on the coil in the concentrator, the distillate will be sufficiently heavy and need not be concentrated more. If, however, dynamite grade is to be made, the distillate is t o be concentrated to gravity while the still is being washed. This is accomplished by closing the valve on the vapor pipe next to the cooler before breaking the vacuum, thus separating the concentrator and condenser from the rest of the set, the small connections from the vapor line below the cooler having also been closed. Operation of the pump and condenser is continued, having full steam turned on t o the concentrator coil and the exhaust open to the sewer. When the desired gravity is reached, a s shown by testing a sample removed by means of a sample tube (not shown), the steam is shut off, the pump stopped, the vacuum broken, and the dist llate pumped to the dynamite bleaching tank. Here it is mixed with beaching carbon (about 1/4 to 1/2 pound per 1000 pounds glycerine-the amount depending on the color desired), then filtered and put into drums. Crudes made from fermented lyes or lyes from fats t h a t have not been washed before going to the soap kettle will always contain more or less trimethylene glycol. The gravity of chemically pure trimethylene glycol is only I .05 and if present in sufficient quantity it is impossible to obtain gravity in making dynamite glycerine. I n this case steam is injected into the concentrator the same as into the still and the glycol distilled Off.
I n making chemically pure glycerine, the first distillate is bleached with carbon the same as in the case of dynamite grade and redistilled. If the same still is to be used for the second distillation, it is necessary t o remove all trace of the foots in washing the still. The best practice is t o have a second still for this redistillation. The bperation for the chemically pure distillation is exactly the same as in the case of dynamite grade except that the sweetwater evaporator is always started with fresh water t o avoid the odor of sweetwater from the crude. Not so much steam is required, however, in this operation and the sweetwater evaporator is operated so as to maintain vacuum in the evaporator from one t o two inches less than a t the pump. The slower the distillation is, the purer will be the distillate. Steam is turned on t o the concentrator coil so t h a t the distillate at the end of the run will have a gravity of about I ,253, a t which it will contain at least 95 per cent. absolute glycerol. This distillate is pumped t o the bleaching tank and mixed with bleaching carbon by means of air. About five pounds of carbon per 1,000lbs. of glycerine are added. It is then filtered and drummed. Here again the presence of trimethylene glycol will cause trouble. While not qbjectionable in pure glycerine on account of gravity, it gives the product a n acrid taste, which cannot be gotten rid of, as it is a property of the glycol. When redistilling to avoid bad effect of glycol, the first I O per cent. distilled should be taken off and kept separate. I n this manner any butyric acid present is also gotten rid of. The first IO per cent. can be mixed with the crude and again be distilled, but unless dynamite grade is produced and some glycol gotten rid of t h a t
2 93
way, the first .IO per cent. of the second distillation would eventually become chemically pure glycol.
NOTES AND CORRE3PONDENCE. DETBRMINATION OF SULPHUR IN BRASS AND BRONZE. For the determination of sulphur i n brass and bronze, the method heretofore used has been rather circuitous by oxidizing the borings, filings or sawings with aqua regia, or with a solution of chlorine or bromine, repeated evaporation with HC1 to remove the nitric acid or the other oxidizing agents, digesting with sodium carbonate filtering from the rather voluminous precipitate, and determining the sulphur in the filtrate by precipitation ,with barium chloride in the ordinary manner after proper acidulation. The writer has attempted to adapt the method used for years for the determination of sulphur in organic compounds to the making of sulphur determinations in brasses and bronzes, and has been able to obtain thoroughly satisfactory results in the following manner. With the aid of a mill-cut file, fine enough to make filings which will easily pass through a Ioo-mesh sieve, filings of the metal are prepared (file across machined face of test bar) and passed through a sieve. Any small particles of iron from the file are removed with the aid of a magnet. One gram of these filings is thoroughly mixed with 6 grams of a powder consisting of z parts of potassium chlorate and one part of sodium carbonate. I n a wrought iron crucible there is first placed a small quantity of sodium carbonate t o cover the bottom, then the mixture of the filings with the carbonate and chlorate is carefully transferred into this crucible, and finally the whole mixture is again covered over with a small quantity of sodium carbonate and chlorate. The crucible is then covered with a porcelain cover, and heated first slowly and then to a fairly high temperature over a Bunsen flame until the whole mass is thoroughly melted. The fusion after cooling is digested with hot water. The salts which contain all the sulphur as sulphate, are filtered from the oxide residue, the filtrate is acidulated with hydrochloric acid and boiled t o remove all carbonic acid. The solution is then neutralized with ammonia and made slightly acid by carefully adding hydrochloric acid until an acid reaction appears, and then 2 or 3 drops in excess are added. The solution is then brought to boiling, and a boiling solution of barium chloride is added. Letting the solution stand for one-half hour in a warm place, but not boiling i t further, all the sulphur will be precipitated as barium sulphate, which can then be readily filtered and washed. The weight of the barium sulphate times 0.13734is equivalent to the weight of sulphur in the sample. Csing a n iron crucible does not appreciably increase the figures obtained, as the sulphur taken up from the iron amounts, at the outside, t o l/loo t o z/l,o of I per cent. If great accuracy, however, is required, a silver crucible can be used, or a nickel crucible. It is self understood of course, that all the reagents must be tested for a possible presence of sulphur before they are used GUSTAVTHURNAUER. in this method.
.
LABORATORYOFTHL AURORA METAL Co., AURORA, ILL.
THE WATER OF THE COLUMBIA AND WILLAMETTE RIVERS. I n the course of some soil investigations which are being carried out at this Station we have had occasion to collect
