The new rapid-hardening cement - Journal of Chemical Education

The new rapid-hardening cement. J. Chem. Educ. , 1925, 2 (7), p 587. DOI: 10.1021/ed002p587.1. Publication Date: July 1925. Note: In lieu of an abstra...
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VOL.2. NO. 7

O B ~ C T I VINBTBACHING ~ CHEMISTRY

587

VI. Dewelopment of moral law and religious attitude in daily life. Education that does not inculcate respect for the rights of others is negative education. There is general recognition of too much neglect of this objective in modern life. The boy and girl scout organizations have furnished splendid examples of effective religious training. Their effectiveness lies in the fact that pupils put into practice the principles taught according to statements of objective IV. The honest student of science cannot be irreligious or atheistic for "It is a sublime conception of God which is furnished by science, and one wholly consonant with the highest ideals of religion, when it represents Him as revealing Himself through countless ages in the development of the earth as an abode for man and in t h e age-long inbreathing of life into its conctituent matter, culminating in man with his pir ritual nature nnd all his God-like powers."-Joint Stntement upon the Rdationi of Religion and Science by Forty Eminent ~cientists,Religious Leaden, and Men of Affairs. "I ain not a subscriber to any religious creed, but I know from my study of science Karl Guthe. that there is a Creator of the univene."-Dr. The New Rapid-Hardening Cement. A o i t i d report has been made by Dr. Oscar Faber, consulting engineer t o H. M. Office of Works, and one of the leading Btitish avthoritics on cement, upon the recently-discovered rapidhardening British Portland cement "Fermcrete," a material by means of which many English local a"thoritie4 are already shortening the period of work upon house building, mad making and repair, ctc., by many dam. Tests made under Dr. Faher's svpervision a t the City and Guilds Eneineering College, South Ken~ington,revealed that concrete cuber made of the new cement have crushing strengths 3% times as great as ordinary cement a t 4 days, 3% timer s~ great a t four weeks, and 2% times as great at three months. Reinforced concrete beams made with the new eement will stand a breaking load approximately a times as heavy a t 4 days, twice as heavy a t 4 weeks, and 1% timer as heavy a t 3 months ar beams made with ordin.ry cement. There is indication, he adds, that these last-mentioned ratios (in each cane) arr maintained at greater ages. Copies of the report are available free of charge fmm the Bdtinh Portland Cement Association, 20 Dartmouth Strept, London, S. W. I-Chcmicol Ncw. Couoids

occupy

WILLAHAN AND

stage a t Minnesota.

J. J.

L. H. RBYBRSON, University

of

Minnesota. For the third time in as many years a group of scientists convened from all parts of this country and from Europe to devote their undivided attention for a few days t o the colioidal state of matter, when the third annual Colloid Symposium, under the auspices of the Colloid Committee of the National Research Council, met a t the University of Minnesota on June 17, 18. and 19.

Although no new eoncepta of importance were presented, practically every phase of theoretical and applied colloid chemistry a s s touched upon, including soils, catalysts, paint pigments, pmtoplasm, soaps, emulsions, orientation of molecules, electrokinetic potentials, photographic sensitizing substance., bacterial toxins, blood coagulation. a1uminvm not. in water purification, plasticity of rubber, and motion pictures of colloids as seen in the ultramierorcope. To the teacher of chemistry, the fmt that molecules tend to otientthemselveson theaurfaas and interfaces of liquid-, is of considerable interest. For instance, in any alcohol the OH groups tend t o stay in the water and the alkyl g r m w to project themselven out of the water. In some other solreoto the reverse is true. The same holds true far the carboxyi group in fatty acids. These phenomena aid in explaining the change in sohbiiity as we proceed along an homologous series. Another fact of interest to teachers is that when hydmgen is adsorbed in s silica gel, it aeta s s a metal surface, taking its proper position in the electrochemical series. For example, it will not displace nickel but it will silver and palladium. If wa. announced that when a virulent evlture of diphtheria organisms is treated with a soap. as sodium rieinoleatc, the soap ir adsorbed on the surface of the organisms. This reduce. their sudace tension, with the result that when they are injected into a guinea pig, they no longer show toxic symptomr. They still, however. have the power of inducing the formation of antibodies. The movies ~howingthe Bmwniao movement o l colloidal particles under the ultramicroscope, and their coagulation under certain conditions. demonstrated a new means of inrtrvction in this field of chemistry.