November 27, 1914] 



SCIENCE 



773 



Three determinations by this method gave 181.30 

 for the atomic weight. From one to two days 

 were allowed for the equilibrium to become estab- 

 lished. A further study of this equilibrium, how- 

 ever, showed that from three to five days were re- 

 quired. A final series of determinations is now 

 in progress. 



W. D. Harkins and E. C. Humphrey: The Capil- 

 lary and Electrical Forces at the Interface be- 

 tween Two Liquids. 



A method which gives very accurate determina- 

 tions of the capillary constant at the interface 

 between two liquids has been devised. The method 

 consists in a measurement of the capillary height 

 under the special conditions which are necessary to 

 secure accuracy. The capillary height method 

 proves inaccurate in all cases where one of the 

 liquids gives an alkaline reaction. For such liq- 

 uids the drop-weight method may be used. This 

 method has been adopted largely by workers in the 

 field of colloidal chemistry, but without any use of 

 the corrections which have now been determined. 

 Since these corrections frequently amount to as 

 much as 37 per cent, they should not have been 

 neglected. 



The latter method has been used to investigate 

 the relation between the change of the surface ten- 

 sion and the change of the electrical potential be- 

 tween two non-miscible liquid phases, in order to 

 see if the relationship is such as would be in ac- 

 cord with one of the theories of muscular motion. 

 This theory is in short that in muscular motion 

 the muscle changes from a neutral to an acid re- 

 action, that this causes a change of electromotive 

 force between two different phases (of the order 

 of one volt), and that this in turn gives rise to 

 such a change of surface tension at the neutral 

 point as was found by von Lerch in Nernst's lab- 

 oratory. The present work shows that von 

 Lerch 's results were in accord with the general 

 theory only because of the inaccuracy of his ex- 

 perimental work. 



Herbert N. McCoy: The Solubilities of Badium 

 Compounds as Indicated iy the Solubilities of 

 Analogous Compounds of Calcium, Strontium, 

 and Barium. 



If it be assumed that radium is the fourth mem- 

 ber of the alkali earth group, it is to be expected 

 that the properties of compounds of this element, 

 other than those dependent upon its radioactivity, 

 should be determinable from a knowledge of the 

 properties of corresponding compounds of calcium, 



strontium and barium. A knowledge of the solu- 

 bility relations of radium and barium compounds 

 is of great practical importance, since the former 

 must always be separated from large amounts of 

 the latter in the course of the extraction of radium 

 from minerals. A systematic theoretical study of 

 the problem indicated the chemical and physical 

 conditions most favorable for the separation of 

 these elements. The theoretical predictions have 

 been verified by experiment and as a result a new 

 method of separating radium from barium has 

 been found which is many times as efficient as the 

 best hitherto known. 



S. W. Parr: The Development of an Acid Besist- 



ing Alloy for a Bomb Calorimeter. 



Coals of the Illinois type when burned in an 

 oxygen bomb generate a mixture of nitric and 

 sulfuric acids, equivalent to approximately 30 c.e. 

 of 1/20 N acid. The correction called for as a 

 result of the heat of formation of these acids ap- 

 proximates 100 calories. If in addition some of 

 the metal of the bomb is dissolved, there is gen- 

 erated an additional increment of heat for which 

 a correction can not readily be applied. Hence the 

 use of platinum or gold as a lining for such 

 bombs. 



In April of 1911 the first attempt was made to 

 produce an alloy suificiently resistant to these 

 acids to permit of its use in the construction of an 

 oxygen bomb. The first successful casting was 

 obtained in December, 1911, but this could not be 

 duplicated until quite recently on account of the 

 difficulty experienced in easting the metal in a 

 dense non-porous form free from flaws. 



The alloy is of the nickel chrome type with 

 copper 7 per cent, tungsten and molybdenum from 

 3 to 5 per cent. The standard of reference for 

 solubility is taken as the amount dissolved by 4 N 

 nitric acid at room temperature per 100 sq. cm. 

 per hour. The average amount dissolved for such 

 unit area and time is 0.09 milligram. The orig- 

 inal bomb has had upwards of 1,500 combustions 

 with no indications of corrosion. 



A large number of parallel determinations with 

 a platinum-lined bomb show a full equivalent of 

 acid as indicated by the resulting titrations. Test 

 bars show a tensile strength of 50,000 to 60,000 

 pounds per square inch while a sample of wire 

 gave a tensile strength of 124,000 pounds. At- 

 tempts to roU the metal into sheets have not been 

 very successful, only small areas having so far 

 been produced. 



