August 25, 1916] 



SCIENCE 



285 



" make " and each " break " must occur with a 

 constant velocity. The contact must be made 

 and broken suddenly and firmly and there must 

 be no vibration at the contact points. 



Martin's key 1 has proved to answer these 

 qualities but is not so compact as the key here 

 described. Erlanger's key 2 designed to be 

 used as a " knock over " key is not suitable for 

 use except with a pendulum. 



Such a large number of keys have been de- 

 scribed that one hesitates to add another. It 

 seems, however, that the simplicity of this 

 principle and the ease with which this key 

 may be used merits description. 



In this key the well-known principle of in- 

 duced magnetism is employed. The current 

 for the coils (C and C) is obtained from a dry 

 cell battery (A) so connected through an ordi- 

 nary push-botton key (V) that when one but- 

 ton is down the current passes through one 

 coil (C) ; when the other button is down the 

 current passes through the other coil (#')• 

 The coils contain soft iron cores (x and x'). 

 One iron core (a;) has a brass pin projecting 

 from its center which prevents the steel band 



(B) from touching the core, thus eliminating 

 any possibility of a " dead center " in the 

 swing of the steel band. The contact points 

 prevent the steel band from touching the other 



i Martin, Am. Jour. Phys., XXIX., 1910, 181. 

 a Erlanger and Gerrey, Am. Jour. Phys., XXXV., 

 1914, 384. 



core. The steel band swings in an adjustable 

 brass socket (8), the details of which are 

 shown in Fig. 2. From the steel band a light 

 spring wire (W) leads to a post (P) thus per- 

 mitting free swing. For contact points, plati- 

 num iridium is used (P and P). The one 

 (P) is soldered onto the steel band and has a 

 flat contact surface. The other (P') is soldered 

 onto an adjustable brass pin (D) and has a 

 convex contact surface. T and T' are the 

 terminal binding posts from which connections 

 are led to the induction coil. The whole is 

 mounted on black fiber %" thick, the connect- 

 ing wires being imbedded on the under side. 



The key has not been tested out with the 

 string galvanometer, but has been used in ma- 

 king calibrations and found to give satisfac- 

 tory results. R. E. Lee Gunning 



Northwestern University 

 Medical School 



THE AMERICAN CHEMICAL SOCIETY 



organic division 



C. G. Deriek, Chairman 



H. L. Fisher, Secretary 



The Synthesis of p-Cymene Monocarooxylic Acids 



and of certain of their Derivatives : M. T. Bog- 



ERT AND J. E. TUTTLE. 



The authors have prepared the two possible ring 

 isomers, cymene 2-carboxylic acid and cymene 3- 

 earboxylio acid, from the corresponding bromo de- 

 rivatives by the Barbier-Grignard reaction, using 

 CO, under pressure, and have studied these acids 

 and the following derivatives thereof: Na, K, Ba, 

 Ca, Cu and Ag salts, methyl and ethyl esters, acid 

 chlorides, amides, anilides, hippuric ester and acid 

 compounds, hydrazides, furo- and thio-diazoles. 

 Small amounts of the 2-acid have been obtained 

 heretofore by other investigators and a few salts 

 have been recorded, but we believe that this is the 

 first time that the acid has been prepared in suffi- 

 cient amount for more extended study. The iso- 

 meric 3-acid appears to be entirely new. 



Benzoylene Urea and Some of its Nitro Deriva- 

 tives: M. T. Bogert and G. Scatchard. 

 The preparation of benzoylene urea from anthra- 

 nilic acid, through o-ureidobenzoic acid, has been 

 improved. The nitro derivatives were prepared 

 either from the corresponding nitro anthranilie 

 acids or by direct nitration of benzoylene urea 

 itself. These nitro benzoylene ureas are struc- 



