SOME EXPERIENCES IN DEVELOPING A VOT•ITO_R PLANT AND PROCESS 261 finished product in the tube, but a very accurate measure of whether or not your system is under control. The conditions are so easily held constant that an in-line viscometer with feedback to the control of the system is quite practical. MR. J. M. B•-AKEWA¾: Did you do that in fact? TaE L•.CTUR•.R: We did try a large number of in-line viscometers but I do not think we ever reached a conclusion on which one we would ultimately adopt. I would like to point out that this plant did not go into production ultimately because there just was not enough toothpaste to keep it running 24 hr per day at that time. MR. A. J•AcocK: What was the horsepower of the motor in the first stage, and that of the motor which turned the rotor in the second and third stages? T• LECTURER: I am sorry to say that my memory is completely deficient on this point. The makers, Johnson & Co., can provide data on this, as they have these plants in a number of different outlets. MR. C. GAMALATGE: I can state that the pilot plant's motor was 2 hp.

Book reviews DREIRINGE MIT ZWEI HETEROATOMEN. E. Schmitz. Pp. xi d- 170 d- Ill. Springer-Verlag, Berlin/New York. DM 58. $14.50. In this volume, the ninth of the well-known series entitled "Organische Chemie in Einzeldarstellungen" (organic chemistry in monographs), we find a survey of the preparation and chemical properties of three recently-discovered classes of organic compounds: (a) The oxaziridines R'x. / N-R" C I (discovered in 1952) R/ NO (b) The diaziridines (c) The diazirines R' N / N-R" c I R / 'XN-R ' (discovered in 1958) R'. /N XC--II (discovered in 1960) R/ XN All these products have one common feature: a three-membered ring containing one carbon atom and two heteroatoms. Contrary to what one might expect, many of the compounds seem to be quite stable, and one of them is already on the point of becoming industrially important {viz. as an intermediate during hydrazinc-produc- tion). This book will prove to be of great interest to all who have their eyes on the new horizons in organic chemistry. G. CARRIERE ORGANOMETALLIC COMPOUNDS. Vol. 1. 2nd edn. Editor: M. Dub. Pp xvii d- 828. (1966). Springer-Verlag, Berlin/Heidelberg/ New York. DM 98. The problems which have been encountered by Chemical Abstracts in keeping up with an ever-increasing deluge of chemical literature are comparable to those of individual workers who have themselves to keep up with Chemical Abstracts. This problem is magnified when one wishes to research a new field. This series is the approach of one publisher to a solution to the problem. By carefully limiting the terms of refer- ence, he has done a service to a segment, albeit small, of the scientific community. In essence, this large volume is a summary of Chem. Abstracts references to the organic derivatives of the transition metals of groups III to VIII of the periodic table (listing only compounds having a carbon-metal bond). The only other apparent source of information used has been Dissertation Abstracts. The period covered, 262