INDUSTRIAL A N D ENGINEERING CHEMISTRY
986
A large number of metals were tried; all the common ones, and several of the rarer. They were used in the form of colloidal solutions prepared according to Bredig’s well-known method of arcing between poles of the material immersed in kerosene. Particles of many degrees of subdivision were obtained by this process, the coarser ones being separated by filtration before the solutions were tested. The test apparatus was a single-cylinder Delco-light plant, of the same type as that described by Midgley. The tests were carried out by first running the engine on loudly knocking kerosene, then switching t o one of the solutions of the various metals in the same kerosene. There were apparent differences in catalytic activity among the different metals a t the same approximate degree of subdivision, colloidal copper giving a t that time the most promising results. However, i t seemed very probable t h a t the activity of any one metal must be largely a function of its degree of dispersion. No exact determinations of particle size were made a t that time. The writer has always felt that the difference between the striking effect of tetraethyl lead and that of a colloidal solution of any one of a number of metals must be principally, if not solely, one of degree. The chance conditions of the experiments conducted by the writer brought about a very positive knock suppression with the colloidal solutions that were used; the most potent solution held the metal in the highest degree of dispersion. A more elaborate method of preparation would have given a still higher degree of subdivision and no doubt a stronger knocksuppressing effect. The metal in molecular dimensions was the next logical step, and as applied by Midgley and Boyd, it represented the ultimate degree of fineness and solved the practical end of the problem. The writer believes t h a t the further investigation of the activity of finely divided metals in promoting the smooth combustion of gas-engine mixtures will produce important results. It is quite possible that metals other than lead, in organic or other co‘mbination, will yield such “supercolloidal” metallic mists in the combustion chamber as t o provide even superior carriers of oxygen or “de-ionizers,” and will disclose the ultimate knock suppressor. The study of knock suppression with colloidal metals would, also, simplify the problem since there is no previous decomposition of the catalyst t o be taken into account. ALANR. ALBRIGHT 1618 BEVERLY ROAD
N. Y. BROOKLYN, June 30, 1926
Factors Influencing the Corrosion of Iron Pipes Editor of Industrial and Engineering Chemistry: There appeared in the April issue of THISJOURNAL a n article under the above title by John R. Baylis. Mr. Baylis has obtained remarkable and valuable results by his systematic treatment of the Baltimore city water supply, but in this article we believe t h a t he has made several statements to which exception should be taken. In the first place we do not believe that he has correctly interpreted the corrosion literature t o which he refers. For example, Mr. Baylis states t h a t “it has been assumed by several writers t h a t the p H of the water between about 5 . 5 and 9.5 has no influence on corrosion rates.” It is a fact t h a t in Cambridge water, which is relatively soft, changes in p H over the range specified by Mr. Baylis do not affect the corrosion rate appreciably when these changes in p H are brought about by the addition of sulfuric acid or sodium hvdroxide. These limitations are clearly specified in the paper t o which reference is made.’ 1
THISJOURNAL, 16, 665 (1924).
Vol. 18,No. 9
The tests on which these statements are based were run by passing natural water past commercial steel plates and through steel pipe. and in many cases extended for periods of over a month. We therefore feel t h a t they approximate conditions of service with the Cambridge water supply at least as well as the tests reported by Mr. Baylis’ approximate conditions with the Baltimore supply. We recognize as well as Mr. Baylis t h a t harder waters may, and do, cause very different results. Determinations of soluble ferrous iron form the basis of most of Mr. Baylis’ argument, b u t unfortunately important details regarding the experimental method which he used were not given in the paper. We have been hoping t o learn these details from Mr. Baylis, but unfortunately lack of time has not permitted him to give them to us. In view of the importance of his results, we believe t h a t these details should be printed. Otherwise, it is difficult t o agree with him on the validity of his conclusions. Mr. Baylis states that “the problem in treatment of water to prevent corrosion is t o produce conditions nearest ideal for the precipitation of all the products of corrosion at the point where corrosion is taking place-that is, where every tendency to corrode will quickly form insoluble compounds.” We believe t h a t this is one of the problems and that another, of major importance, is to cause these insoluble compounds t o adhere t o the metal surface on which they are precipitated. R . P. RUSSELL W. G. WHITMAN RESEARCH LABORATORY OP APPLIED CHEMISTRY MASSACHUSETTS INSTITUTE OF TECHNOLOGY CAMBRIDGE, MASS. July 26, 1926
A. C. S. Acrostic AMERICAN CHEMICAL SOCIETY A. D. 1876 Id A ho Ver M ont Tenn E ssee Neb R aska M a I ne Wis C onsin A1 A ska K a N sas North C arolina Was H ington Conn E cticut Wyo M ing Miss I ssippi Mi C higan Alab A ma Co L orado Mis S ouri I O wa South C arolina Ar I zona New M E xico Mon T ana New Y ork
Del A ware North D akota New J E rsey Cal I fornia W. Vir G inia 0 H io K e n T ucky G E orgia Minn E sota Illi N ois
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Okla H oma D. Col U mbia Virgi N ia I n D iana Flo R ida Massachus E t t s South D akota N. Hamp S hire Or E gon Pennsyl V ania N E vada Arka N sas U T ah Mar Y land Loui S iana Rhode I sland T e X as
Composed and dedicated to the AMERICAN CHEMICAL SOCIETY by Calixte
F. Bousquet, Los Angeles, California. This acrostic illustrates well the national character of our SOCIETY, being composed of fifty letters, each one selected from names of states, territory, and federal district.
Note-On page 875, August issue, we reviewed Webre and Robinson’s book on Evaporation and quoted a price of $6.00. The publishers advise that the price has been advanced t o $8.50 a copy.
