Oct., 1916
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congregates in schools, theatres a n d assemblies of various kinds. T h e statistics of every health department bear this out. T h e crowd-contagion danger is undoubtedly greater in a swimming pool t h a n under ordinary conditions for two reasons: jirst, water is a better transfer mediuri? for bacteria a n d infectious material t h a n air; second, in swimming pools there is coughing, clearing of nostrils, sometimes spitting, together with t h e probability t h a t some one will snuff t h e water or even swallow it. There is no system of filtration or sterilization yet known t h a t will absolutely safeguard this contingency. Infectious matter from t h e mouth or nostrils might be passed between adjacent swimmers even if t h e water were a dilute solution of disinfectant. Is this a serious indictment against t h e swimming pool? I believe not, for t h e reason t h a t sick people d o not visit swimming pools as often as they might mingle in crowds, for example. Furthermore, those using swimming pools are usually athletically inclined a n d not easily susceptible t o infection. No doubt t h e exhilaration, quickened circulation, etc., incident t o such exercise makes for special resistance at t h e time. The possibility of “disease carriers” innocently mingling with those using such pools must be conceded. Certainly i t is t h e d u t y of those having charge of indoor swimming pools t o take every precaution t o protect their patrons. Refiltration and sterilization, together with t h e strict enforcement of t h e preliminary shower with soap, are t h e accepted primary measures. I n addition, t h e t a n k room should be kept scrupulously clean and well ventilated. There should be sufficient equipment for expectoration, a n d floor talks should be frequently given, explaining t h e necessity of cooperating in keeping t h e pool clean and wholesome. T h e dangers of carelessness should be pointed out a n d a group consciousness on t h e matter of thorough preliminary showers and t h e proper use of cuspidors should be created. When all this has been done, there should be established a strict inspection and exclusion r6gime. Every cough or skin infection should be forbidden entry t o t h e tank. With these precautions, conscientiously enforced, t h e swimming pool is certainly as safe as any other feature of gymnastic or athletic activity. If t h e records prove anything, indoor swimming compares most favorably in t h e matter of injury and mortality statistics with such accepted sports as football, hunting, boating, etc. Acknowledgment is herewith made t o Mr. A. F. Whipple, former graduate student at Northwestern University, for part of t h e analytical data used in this paper. EVANSTON, ILLINOIS
EXTENDING THE USEFULNESS OF A SHAKING MACHINE’ By ROBERTM. CHAPINAND JACOB M. SCHAFFER Received May 27, 1916
A shaking machine, if not a necessity, is a t times a great convenience in a n y laboratory. But t h e purchaseable types of machines are in general each adapted t o only a single kind of work, so t h a t a complete equipPublished by permission of the Secretary of Agriculture.
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ment demands two or more different machines, which may easily deter one from t h e purchase of any. The purpose of this paper is t o describe simple attachments whereby one machine may have its usefulness a t least doubled. T h e machine referred t o is of a well-known type,’ in which an oscillating platform is driven b y a vertical bent axle, t h e platform being prevented from rotating b y cogs in its sleeve meshing with cogs fixed t o t h e frame. The platform is constructed t o carry 6 flasks, t h e necks of which are held in 6 spring clamps radiating from a central collar about t h e sleeve. T h e first discovered extension in t h e possibilities of this machine was its use as a sieve shaker. The collar holding t h e spring clamps is raised and fastened so t h a t t h e plane of t h e radiating limbs of t h e clamps is slightly above t h e end of t h e sleeve. Upon t h e center of this skeleton platform is placed t h e charged sieve or sieves, with cover a n d receiver. I n t h e sieve itself must be placed a couple of pebbles or balls of flint, iron or porcelain, t h e motion of which will prevent clogging. But slight ingenuity is then needed t o lash t h e whole down with cord, or with what is in. rawhide belt-lacing. much better, a length of From satisfactory results as a sieve shaker, t h e use of t h e machine as a shaker for liquids naturally developed. A cradle must be constructed of appropriate form for t h e work in view. T h e one illustrated in t h e figure, made of hard wood a n d faced with leather, will carry separatory fpnnels or bottles up t o 2 liters capacity. When t h e cradle is set on t h e radiating clamps, t h e collar carrying t h e latter being fastened in its lowest possible position, t h e projecting end of t h e sleeve enters t h e hole in t h e center of t h e base of the cradle, while t h e two trapezia beneath t h e base fit between adjacent clamps. Then pass a bight a t t h e middle of a length of rawhide belt-lacing under t h e clamp projecting a t either A or B , carry t h e doubled lacing over t h e base of t h e cradle, once or twice around t h e opposite clamp, pass between t h e spring leaves of t h e clamp, and draw tight. Now place in position t h e bottle or separatoryfunnel, and pass t h e lacin: back a n d forth over i t and around t h e two clamps, finally securing t h e ends as before. If t h e container is 4” tah eglobular lacing separatory is best passed funnel
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over t h e neck and t h e throat -.--.---.---.. 1-.---just above t h e stop-cock. The idea is t h e import a n t thing here presented, 5’ , and hence the simplest possi- , B ble t y p e of fittings has been described. One may elaborate on t h e idea as much as circumstances warrant. I n this laboratory t h e cradle now in use has t h e large hole in t h e base bored only about half way through from t h e bottom, A where it is met by a ‘/4 in.-hole, bored on t h e same cen1 It is contrary t o the policy of the Department of Agriculture under such circumstances to refer to a proprietary article by name.
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ter. Through t h e l a t t e r hole passes a wing-headed screw bolt which enters a female screw threaded into the oil hole found a t t h e upper end of t h e sleeve. The head of the bolt plays on a countersunk iron washer. The container t o be shaken is secured in place b y a leather band and clamp permanently attached t o the cradle. With proper speed adjustment t h e shaking is thoroughly effective, while either form of cradle is quickly demountable if the machine is wanted for its originally intended use as a flask-shaker.
I By W . C. CARKELL
Received June 19, 1916
The development and progress of the Chemical Industry is vitally dependent on the development of materials out of which the plant equipment may be constructed. A process that is a success in the laboratory will be a success in the factory, if conditions are duplicated. platinum and glass are available in the laboratory, but may be prohibitive in the factory. .Platinum a t Sgo.00 per Troy oz. was used for the manufacture of concentrating stills for sulfuric acid; platinum a t s9j.00 per 02. cannot be considered. Glass has its place, but a t best is unsafe For extensive processes, The branch ot; the chemical industry that suffered most for materials out of which t o construct apparatus was the mineral acids division. For many years various metals and alloys were offered for which more or less acid-resisting properties were claimed. They had their uses but as complete acid-resisting materials they were not successful. With the advent of fused silica a decided advance was made, and it successfully replaced platinum in a number of processes. In 1911 a basin of fused silica was tried out a t the factory with which the writer was connected; so successful were the results t h a t a Io-ton cascade concentrating plant for sulfuric acid was erected to replace a platinum outfit. The results were all that could be desired. The acid made was even better than that made in platinum. Fused silica is brittle and costly and must be handled with as much care as glass. I n 1913 a material under the trade name of “Feralun” was tried out. This was a mixture of cast iron and an abrasive, the abrasive being a n alloy of aluminum and silicon. The surface of the iron was covered with the abrasive. The abrasive was acid-resisting, but the acid soon destroyed the iron, leaving a porous maqs. However, we found “Feralun” useful for nipples on acid tank cars. FUSED szicoN-Silicon has acid-resisting properties that are all that could be desired for sulfuric acid, b u t it is more brittle than fused silica, and its use has not been very extensive. “ F E R X O cIiRcME”-This alloy is made by the Electro Metallurgical Co, of Iiiagara Falls, and is a very promising product. Glacial acetic acid does not attack i t ; j 6 and 2 8 per cent acetic acid attacked it slightly. Strong and weak nitric and sulfuric acids have practically no effect on the alloy. Hydrochloric acid attacked it readily. The experiments were carried out in a bowl 18 in. in diameter and 6 in. deep. SILICON A N D IRON aLLou-The materials thus far mentioned are valuable for specific purposes. The real dawn of acidresisting alloy came with the use of “silicon iron” alloy. The beginning of the use of this alloy was about 6 yrs. ago. The 1 Read h e f o r e t h e Eighth Semi-Annual Meeting, American Institute of Chemical Engineers, Cleveland. June 16, 1916.
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A minor drawback t o this t y p e of machine is a tendency t o pound sometimes under a n imperfectly balanced heavy load. I t would seem t h a t this might be overcome b y better designing of the cogs. Meanwhjle t h e pounding may be considerably lessened if a cup made from a pipe cap is fitted around t h e lower cogs, and filled with grease mixed with sawdust or granulated cork. I n extreme cases a clamp or other weight may be fastened t o the light side of t h e platform, BIOCHEXICD I V I S I ~ XB,U R E A UO F AXIMALINDUSTRY, U. S. DEPARTMENT O Y AGRICULTURE, WASHINGTOY
ADDRESSES ACID-RESISTING ALLOYS’
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first advertisement the writer observed of this alloy was in the Joumal of the Society of Chemical Industry, January 15, 1912. This was of a silicon iron alloy, “tantiron,” put out by the Lennox Foundry Co., Ltd., of London, England. I n May, 1912, after a year of experimenting, the first silicon iron alloy in the Cnited States was put on the market under the name of “Duriron,” by the Duriron Castings Co. of Dayton, Ohio. In 1913 the American rights for “Tantiron” were taken over by the Bethlehem Foundry and Machine Co., of South Bethlehem, Pa. “Ironac” is another trade name for a silicon iron alloy made by the Houghton Co., Ltd., of London, England. While these are all alloys of iron and silicon, their composition is not the same. Silicon iron alloy as put out under the above names is very resistant to all strengths of sulfuric acid, and apparatus made of this alloy is used in all forms of concentrating vessels and cooling devices for the concentration of sulfuric acid. By the use or the so-called “cascade basins” set in a proper furnace, full strength oil of vitriol is made from j O o Be. acid. If all the fittings and coolers are made from this alloy the resulting oil of vitriol is practically free of iron after the plant has been in operation a few weeks. \%’here brimstone acid is used the resulting oil of vitriol should not contain over o.oooz per cent iron. For sulfuric acid concentration, the alloy is durable and the breakage is very small. -4plant properly handled will run for months without a shut-down. The success of the modcrn tower system for concentrating sulfuric acid has been due largely to the use of pipes and fittings made of this alloy. Silicon iron alloy castings have extensively replaced stoneware parts for the manufacture of nitric acid. Early in 1916 the demand for nitric acid increased to enormous proportions; extensions to old nitric acid plants and the erections of new and larger plants was immediately demanded. The capacities of the stoneware factories of the country were soon taxed t o their limit. Deliveries could not be made under 6 months, if a t all. Had the production of nitric acid been dependent upon stoneware as it was a few years previous, the production of nitric acid would have been greatly curtailed and the story of the ix‘orld’s \Tar would probably be different. The silicon iron alloy is resistant to nitric acid of various strengths. I t can be cast into all the various forms required for nitric acid apparatus. Castings can be made as readily and as quickly as can those made of cast iron. Here was the ideal substitute for stoneware. h’ecessity compelled its use and to-day it has largely superseded stoneware for nitric acid production. X large nitric acid plant equipped entirely with this alloy in the form of “Duriron” was in service for 8 mo. and the alloy showed no indications of corrosion or deterioration. There was practically no breakage. Fire destroyed the building housing the plant and most of the supports for the apparatus. The fire did not harm the castings, though they were exposed to intense
