October, 1925
I N D U S T R I A L A N D ENGINEERING CHEMISTRY Laboratory Centrifuges
The development of a laboratory basket centrifuge in which the basket is made of high-grade porcelain and the drainage chamber is of glass-enameled cast iron has been accomplished by the International Equipment Company. The basket and its acid-proof drainage chamber may readily be used instead of the ordinary revolving tube heads without alteration of the machine itself. The change from one head to the other requires but a few minutes. A vibrationless stand upon which the centrifuge together with its motor and electrical control may be mounted has also been developed by this company. This stand absorbs practically all the vibration from the machine and is mounted on rubber-tired casters eo that the whole may be readily moved from place to place. Boiler Room Control
The immense cost of power production and the apparently unavoidable low efficiency of steam plants generally has been a constant spur to engineers to minimize the various small losses connected with them. The saving of the slightest percentage of power cost amounts to so much in mass that the reward is extraordinarily great. With such a st>imulusit is not remarkable that scientific apparatus makers have devoted much attention to instruments for more accurately controlling the production and utilization of heat. I n a similar way the delicacy of many chemical processes involving heat transfer has necessitated the development of accurate devices for recording and controlling temperature. An electric meter for automatically indicating and recording the percentage of carbon dioxide in flue gases, which can also be used to indicate and record other gases, such as sulfur dioxide, has been perfected by the Brown Instrument Company. This instrument operates on the principle of thermal conductivity in conjunction with a Wheatstone bridge. One electrically heated platinum wire is surrounded by air and another by the gas under analysis. The difference in temperature of these two wires is proportional to the composition of the gas and may be read off as in an ordinary resistance thermometer. This instrument eliminates chelnicals that must be replaced, makes possible readings a t any desired distance, and indicates continuously, instead of intemittently, the percentage of carbon dioxide in the gas. The Eddy smoke recorder designed to show a continuous record of the quality of smoke from a stack is among the recent developments of the Gaertner Scientific Corporation. This instrument continuously sucks smoke from the stack, dries it, and deposits the soot in a narrow band on a sheet of white paper. This sheet is constantly rotated and records a complete day's performance in fourteen bands, side by side. The clogging of valves has been overcome by blowing steam through the instrument each time the record is changed. A recording boiler level gage has been developed by the Foxboro Company to make easier the proper control of water level in a boiler. Both indicating and recording types are available and they may be placed a t any convenient point for easy reading. These instruments supplement the ordinary gage glass on the boiler drum and make it rnuch easier for the boiler operator to read his levels in addition to providing an exact permanent record. Temperature Control
Various types of indicating and recording thermometers are on the market and these are being constantly improved. The C. J. Tagliabue Manufacturing Company has recently brought out a mercury-filled recording thermometer which may be used with a connecting tube as long as 60 meters (200 feet), a special device compensating for changes of temperature over
1017
its length. The Wilson-ll-laeulen Company has added to its line improved forms of resistance bulb electrical thermometers, making them applicable for wide range of industrial uses up to 480" C. (900" F,),an automatic temperature controller of the potentiometer type, and an improved recording pyrometer capable of making single records, duplex records side by side, or in multiple form as many as twelve records on one chart. The Foxboro Company has improved its recording thermometers by a new type of hub for holding the chart in place. A nonrecording humidity controller in which the wet and dry bulb scales are separate and calibrated for the entire range of the instrument has been brought out by the Foxboro Company. The temperature elements of this instrument are replaceable as a unit and easily accessible for overhauling. No rubber tubing or other parts subject to deterioration are included, and the instrument may be used in processes and operations where continued and severe strains are met. Oil Prospecting
The Eotvos balance for detecting and mapping oil deposits has been greatly improved as to ease of operation and sturdiness of construction for use in the field by the Gaertner Scientific Corporation. The laborious nature of the operation of old forms of this apparatus greatly discouraged its wide use, but with the new form it is possible to carry out a complete set of observations a t a single station in an hour. Rubber Aging Tests
The apparatus described in THISJOURNAL, 16,711 (1924), and 17, 860 (1925), by Bierer and Davis, for the accelerated aging of rubber is being offered by the Emerson Apparatus Company. It consists essentially of a bomb in which the rubber under test may be heated in the presence of oxygen under pressure. I n this way it is possible to secure the effect of several years' natural aging in a few hours. A new multiple stirrer for the simultaneous stirring of six beakers has been developed by the L. E. Knott Apparatus Company. The stirrers are operated by a 110-volt (either a. c. or d. c.) electric motor and are driven through friction drives in such a way that the speed of each may be regulated independently of the others. Conclusion
Many of the makers of equipment of this type have been a t work on apparatus which they are not yet ready to offer the public. Others report that their activities during the past year have been devoted entirely to mechanical improvements in their manufacturing processes or products and that the results have therefore been of little general interest. The results of the labors of these essential servants of science are manifest in the immense amount of accurate and important research work that is being continuously published in this country. The increasing activity of research in all lines in this country is placing upon them a serious responsibility which they will not fail to assume. Their opportunities for service in this age of the "Fifth Estate" are boundless.
Making Stronger Concrete Water is an important ingredient in concrete. Experiments just completed a t the Bureau of Standards show that this is just as true with the new quick-hardening high-alumina cements as with Portland cement. The Bureau of Standards finds it important to select sand and gravel in proper size gradation, since less water is required t o make the concrete workable and a greater strength results. I n one experiment a decrease of 1 per cent of water was found t o increase the strength as much as 26 per cent.
