50 Browning — Method for the Quantitative 



Conclusiotis. 



I. The generally accepted law of elastic lengthening ce=aP, 

 according to which the lengthening x is proportional to the 

 stretching weight P, is only an approximation. 



II. The relation between elastic extension and stretching 

 weight can be expressed by an equation of the following form : 



X=a'P+/iP 2 4- r P 3 



III. The modulus of elasticity of the undeformed body can 

 be calculated with the help of the equation 



IV. The true moduli of elasticity calculated in this way 

 may be as much as 10 per cent larger than those determined 

 in the ordinary way. Consequently it will be necessary to 

 recalculate physical constants which depend on the modulus of 

 elasticity. 



Haverford College Laboratory. 



Aet. YI. — A Method for the Quantitative Separation of 

 Strontium from Calcium by the Action of Amy I Alcohol on 

 the Nitrates ; by P. E. Browning. 



[Contributions from the Kent Chemical Laboratory of Yale College — XT.] 



At the suggestions of Prof. F. A. Gooch, and following the 

 general mode of procedure laid down in his paper* upon the 

 separation of sodium and potassium from lithium by the 

 action of amyl alcohol on the chlorides, 1 undertook a series 

 of experiments looking toward the separation of strontium 

 from calcium by the action of amyl alcohol on the nitrates. 

 On boiling several portions of the so-called chemically pure 

 calcium and strontium nitrates with amyl alcohol, nearly com- 

 plete solubility was observed in case of the calcium salt, while 

 corresponding insolubility seemed to be characteristic of the 

 strontium salt, and these results seemed to warrant proceeding 

 with the work. 



For the quantitative tests to be described standard solutions 

 of specially purified strontium and calcium nitrates were pre- 

 pared. In general the preparation was effected by precipitat- 

 ing a soluble salt of either element with ammonium carbonate 

 in the presence of ammonium chloride, washing thoroughly 

 with boiling water, dissolving in the least possible amount of 



* Amer. Chem. Jour., vol. ix, p. 33. 



