April, 1931
I N D U S T R I d L BhTD ENGINEERING CHEMISTRY
nection with proposed radio legislation, and his advice was of great value. During Mr. Hoover’s administration as Secretary of Commerce, the research appropriations for the Bureau of Mines were increased, and special funds were obtained for cooperative work with the Geological Survey in the investigation of potash deposits, for developing new and cheaper processes for extracting potash from ores, for research into methods of treating oil shale, and for investigating the applicability of various geophysical methods as an aid in discovery of hidden bodies of minerals and oils. The other activities of a continuing nature under the auspices of the Bureau of Mines must be well known to our readers. The White House Coriference on Child Health and Protection is a scientific approach to a question of public importance and the project is one in which the President is greatly interested. In addition to these official activities, of which we have mentioned but a few, Mr. Hoover has taken an active interest in a number of scientific and educational projects. He served as the chairman of the national committee on the Prize Essay Contest of the AMERICANCHEMICALSOCIETY. He attended and addressed many scientific gatherings of national and international nature; he was accessible for conference on :my worthwhile project designed to advance scientific research in this country; and he placed behind the effort of the National Academy of Sciences to obtain large funds for basic research his advice, his active support, and his leadership. “The Vital Need for Greater Financial Support tg Pure Science Research” was the subject of his address before the American Society of Mechanical Engineers, where he delivered the first Henry Robinson Towne lecture in December, 1925. The work initiated is being carried forward by a committee of distinguished scientists and industrialists, who seek to complete a fund of $20,000,000 for the support of research in pure science. His interest in the better training of men and women which comes from higher education is reflected in the address, entitled “Higher Education and the State Government,” delivered a t the commencement exercises of the University of Georgia in June, 1926. Before the American Association for the Advancement of Science in Philadelphia in December, 1926, he spoke on “The Nation and Science,” discussing certain relationships of research in pure and applied science to public policies and, above all, the national necessity for enlarged activities in support of pure science research. But why continue? It is an axiom in military circles that one should never use more force than is necessary to overcome the adversary. Perhaps we have already disregarded that axiom in the presentation of a few of the things which may be attributed to the continuing substantial interest and sympathetic support which Herbert Hoover, whether as a private citizen, Secretary of Commerce, or President of the United States, has for science and research. It is one thing to be an outstanding engineer or scientist, and quite another to exemplify the best in executives. A combination of these ideal qualifications is seldom, if ever, found. In Herbert Hoover we have the nearest approach to that ideal in any individual whom we have ever had in high office. HARRISONE. HOWE
447
Studies in the Painting of Wood I-Influence
of Wood Structure on Paint Behavior
Editor of Industrial and Engineering Chemistry: Since the publication of our paper under this title, IND.ENG. CHEM.,23, 226 (1931), the attention of the authors has been called to the following statements, in the paper, that might be misinterpreted and should be clarified: (1) “Primary tissue” refers to “important tissue” and is not used in the botanical sense. (2) “Dovetailed fibers” should read “overlapping fibers.” (3) I n speaking of the formation of spring and summer wood, the word “period” should have been “periods” to indicate that alternating seasonal growths are involved. (4) All medullary rays are not continuous from the center of the tree, but from the standpoint of their importance in paint penetrability they are practically continuous through the thickness of average flat-grained boards. Also the surface area occupied by these ray cells is considered by some authorities to be approximately 10 per cent, instead of approximately 20 per cent as stated. ( 5 ) Resin ducts are intercellular spaces and not cells. Figure 16 was intended to show a resin canal, but owing to the low magnification the actual canal does not show although the resin that has exuded from the canal is plainly visible. There are no published data proving that summer wood in yellow pine contains more resin than spring wood. (6) There seem to be conflicting and unsettled opinions among the ranks of wood technologists on points concerning penetration of liquids into wood. The opinions of Scarth [Paper Trade J., 86, 53-8 (April 26, 1928)], used in this paper, are apparently a t variance with the opinions of other wood technologists. The function and operation of the bordered pits is another subject that is open t o controversy and the number of these pits on a given fiber is less than might be supposed by the statement that the fiber walls are “covered with bordered pits.” ( 7 ) The work and data presented relating to the shrinkage and swelling of wood were not complete and may apply only to the particular wood studied. This fact was mentioned in the paper but perhaps was not emphasized sufficiently. The choice of yellow pine for this study was obviously made because it is recognized as a wood which is subject to painting troubles. (8) A mistake due t o a typographical error in Figure 17 shows flat and edge grain surfaces reversed. (9) Figure 5 was intended t o show microscopical differences in wood that might have an influence on paint behavior.
It is hoped that the above mentioned corrections will serve to clarify the text of the paper. J. H. HASLAM S. WERTHAN NEWJERSEY ZINC COXPANY PALMERTON, P A .
March 13, 1931
Sizing by Elutriation of Fine Ore Dressing Products Editor of Industrial and Engineering Chemistry: It is commendable t h a t so many of the students in flotation are giving thought to elutriation. The article by Gaudin, Groh, and Henderson [IND. ENG. CHEM.,22, 1363 (1930)l is a timely one. However, some of the trouble they encountered with sulfides may be alleviated easily. They say:
With material composed mainly of metallic sulfides or other non-polar substances or non-polarly filmed substances, such as flotation concentrates, i t is often impossible t o effect reliable Addition-Subtraction Logarithms to Five Decimal Places. BY I,. M. BERZE- sizing if water is the liquid medium. This derives from the great tendency towards flocculation and flotation exhibited LEY. 135 pages. White Book and Supply Co.,New York. 1930. Price, by non-polar substances. To obtain reliable sized fractions from $3.25. flotation concentrates or other non-polar substances i t is necesProceedings of the Tbirty-third Annual Meeting, Val. 30, 1930. Part Isary t o use another liquid medium than water. Committee Reports, Tentative Standards. 1336 pages. Part II-
New Books
Technical Papers. 1085 pages. AXERICAN SOCIETY FOR TESTING MATERIALS, Philadelphia. Pa., 1930. Parts I and 11, each, paper, $6.00; cloth, $6.50; half-leather, $8.00.
Of all the stubborn and refractory products under the conditions as outlined above, a galena flotation concentrate probably
stands a t the head of the list. Fortunately, howevcr, it may be subjugated so that elutriation can continue in water in n o m 1 fashion. The treatment required is a simple one. Dichromate has long been known to deaden the surface of galena. By the use of it. lead concentrates have been made completely docile. In the first step of preparation the sample is treated with a very dilute solution of sodium dichromate, acidified with sulfuric acid. when the dichromate solution has spent its oxidizing strength (only a few minutes are required). gum arabic is added and the sample is vigorously shaken to complete the deflocculation. Then the wet screening and all the subsequent steps in elutriation will follow with all the precision desired.
The design was evolved after conference with G. G. Griswold. Jr., research engineer for the Anaconda Copper Mining Company, who has used this type of elutriator for the study of mill products. The apparatus is similar to the type described in our paper except that a piezometer is used to control the overtlow. The elutriator wm made from a 250-ec. dispensing burrt. Once calibrated, the piezometer permits rapid setting of the apparatus to secure the desired acetone velocities. An elutriator of the above JcT sire may be used throughout the W I L LH. COOE~ILI. range from 150 to 1600 mesh (1W MlsILs5lrrl VnLLsv l i n i ~ a x l n a i rsrarcoh. to 9rr for quartz). U. S. B U R E A U or MINES, R o ~ m Me. , Uercmb~r31. 1030 It has been found convenient Grst to deslime in water the mate. ..,. rial to be elutriated in acetone Editor OJ IndurLrlal and Engineering Citemislry: This allows the acetone t o be used We are in accord with Mr. Coghill’s statement onceruiiig several times before it is nceessaw to purify it by distillation Con the use of a slightly acid solution of dichromate to deaden tlir surface of galena so tiiat i t may he elutriated in water. We sidcrable economy of amtone i‘ cfTccted, since the d i s t i l l a t i o i i have used the method. losses are rather high with ortii Figure 1 shows a galena pastide whose surface was treated nary laboratory equipment. in an acid dichromate saliition after protecting i t in part witlr E. J. Hall, of Colambia I n i paraffin. The paraffin was removed before photographing. versity, has suggested the use oi The dull portion is that which was etched by the dichromate. Its appearance is due to the formation of lead chromate or a tap water freed of dissolved gases by a vwxurn pump in place of CLAMP mixture of lead chromate and lead sulfate. Our objection to treating galena in the maniier suggested by d i s t i l l e d water. Such watcr is Figure 1 Mr. Cogkiil is twofold Firstly. i t makes analysis for lead in suitable if it does not contain the elutriated products somewhat more difficult. owing to tlic sufficient dissolved substances to cause flocculation or to intruchromate radical. Secondly, some of the coating from the duce adsorbed foreign salt3 in the finest fraction of an elutriated coarse particles may slough off,increasing the lead content of sample. the finest grade. Also, some lead appears to go into solution A. M. GAUDIN and to he precipitated iu the solution, atid not a t the surface J. 0. GROW of the galeria particle-. H. B. H n ~ o s x s o ~
.
MONTANA
SCrou~OP Minas
BUIIB, MONT. January 30. 1951
Corrections In my paper entitled “Purified Woad Fiber. A Study of the Physical and Chemical Properties,” IND.END.CWEM.,23, 131 (1931). the following corrections should be made: The first sentence i t the Method for Determining Copwr Number should read A 3-gram sample of bone-dry shredded nuln is “laced in a 1.5-liter routdlrottomed ffa3k. a wateria&t&’reRux condenser is attached to the flask, 2.50 cc. of iuatw are‘added, and the pulp suspension is quickly brought to the boiling point.” I n the last part of this same method, the liberated iodine is Litrated with 0.20 N sodium thiosulfate. instead of 20 N sodium thiosulfate.
Figure 3
Wc fitvur acetone iwtrad of water for the eiutriatiori of con centrztes, even though the sulljdes may be deadened sufficiently for water elutriation so that there is no danger of inaccuracies from flotation of coarse particles. In addition to tlie fact that elutriation is more rapid in acetone than in water, owing to the Iosv viscosity of acetone, that method gives ckaiier products since it removes effectively any slime coatings from the surface of mincral p;utieles. Since our paper was submitted for publication, another t y w of elutriator (Figure 3) liaz heen put in use for sizing with acetone.
In my paper entitled “Purified Woad Fiber. The PaperMaking Characteristics of Wood Fiber High in Alpha-Cellulose,” IND. ENG. CHEM, 23, 266 (1931), the following comctions should be made: The last Sentence of the synopsis should read: “The presence of suljite wood pulp imparts physical weakness, particularly in
rrspect to tearing resistance and fold endurance.” On page 266, under “Beating in Ball Nlills,” the reference to Figures 1 and 2 should be deleted from the second sentence. On page 267 the caption under Figures 1 and 2 applies only to Figure 1. Figure 2 should be described as “Experimental Paper Machine of the Brown Company.” On page 271, the reference to Figure 8 should be deleted trom the third line above the table in the first column. Figure 4,turn right side to bottom. GBO A. KICETER
