312 Scientific Intelligence. 



scale and conclude that a product corresponding to the " 80 per 

 cent muriate " could be made for about $3 1 per ton. This has 

 previously cost about $37.50 per ton as imported from Germany, 

 and recentty, owing to European conditions, a price of about $100 

 per ton has been quoted. It appears that, if the calculations are 

 accurate, the employment of feldspar as a source of potash is 

 promising. The demand for potash salts in this country is very 

 large, particularly for use as a fertilizer. — Jour. Indust. and Eng. 

 Chem., vii, 145. h. l. w. 



3. A Qualitative Test for Water. — E. R. Weaver has devised 

 a method for detecting very minute amounts of water in organic 

 substances. It is sensitive to less than 0*1 mg. of water, and it 

 depends upon placing the substance to be tested in contact with 

 calcium carbide in the presence of a perfectly anhydrous solvent 

 for acetylene. Any acetylene formed by the action of water is 

 detected by adding the resulting solution to an ammoniacal solu- 

 tion of cuprous chloride. Nearly all the common organic liquids 

 are suitable for the purpose of the solvent if carefully dried. The 

 calcium carbide employed must be completely freed from adher- 

 ing acetylene by adding to it some of the anhydrous solvent to 

 be used and boiling the latter off completely. The test may be 

 carried out by bringing the substance to be tested, the dry sol- 

 vent and a few pieces of boiled out calcium carbide into a test 

 tube. The tube is closed by a dry stopper and shaken occa- 

 sionally for two or three minutes, without allowing the liquid to 

 touch the stopper. The carbide is allowed to settle completely 

 and the clear solvent is decanted into an ammoniacal cuprous 

 chloride solution and vigorously shaken, when the red copper 

 carbide shows that water was present. Of course very careful 

 blank tests must be made with the reagents and apparatus used. — 

 Jour. Amer. Chem. >Soc., xxxvi, 2462. h. l. w. 



4. The Rare Earths ; by S. I. Levy. 8vo, pp. 345. New 

 York, 1915 (Longmans, Green and Co. Price $3.00 net). — This 

 book, which is of English origin, deals in a very satisfactory way 

 with the occurrence, chemistry, and technology of this very mys- 

 terious group of elements. Much dignity is given to the work 

 by a short but extremely interesting introduction by Sir William 

 Crookes, who has made very extensive and valuable investigations 

 in the field of the substances that are here discussed. He says 

 that the rare earths constitute the most striking example of the 

 association of chemical substances with others which are closely 

 allied to themselves, and from which they are separated only 

 with extreme difficulty; that they form a group to themselves, 

 sharply demarcated from the other elements, and that it is his 

 belief that by following the study of them to the utmost limits 

 we may arrive at the explanation of what the elements really are 

 and how they originated, and discover the reasons for their 

 properties and mutual relations. He says, further, that there has 

 long been a need for a work in the English language dealing his- 

 torically and descriptively with these substances, and that Mr. 

 Levy's book is well fitted to till the gap. 



