UCTOKEB 28, 1904.] 



SCIENCE. 



569 



the latter is comparatively moist; in other 

 words, it fails to give us information regard- 

 ing the rate of movement of soil moisture 

 during conditions approximating a drouth. 

 Experiments are now in progress with a view 

 to extending the range of the apparatus. 



L. J. Eeiggs. 

 A. G. McCall. 

 Physical Laboratory, 



Bureau op Soij.s, U. S. Dept. of 

 Agricultdeb, ,October 12, 1904. 



N0TE8 ON INORGANIC CHEMISTRY. 

 The first fall number of the Berichte of the 

 deutschen chemischen Gesellschaft, with its 

 more than six hundred pages, brings aij. un- 

 usually large number of papers on inorganic 

 chemistry. Several of these are of general 

 interest. 



IRON HYDROXID AS AN ANTIDOTE FOR ARSENIC. 



The discovery that freshly precipitated 

 ferric hydroxid is an antidote for arsenic was 

 made by Bunsen in 1834, and was the subject 

 of his earliest scientific publication. He at- 

 tributed the antidotal effect to the formation 

 of a basic ferric arsenite ; indeed, by working 

 in an acetic acid solution he obtained a pre- 

 cipitate of such constitution. The suggestion 

 was, however, early made that it was possible 

 that a finely divided powder, of no physiolog- 

 ical or chemical action, could under certain 

 circumstances be active as an antidote in cases 

 of poisoning, and large doses of magnesia 

 were found by some physicians to be as efiicient 

 as the ferric hydroxid. The whole subject has 

 now been gone over by Dr. Wilhelm Biltz, who 

 finds as a matter of fact that no compound is 

 formed between the arsenic and iron, but 

 that the gelatinous precipitate acts wholly by 

 adsorption. When the iron oxid is present in 

 the proportion of eight parts to one of arsen- 

 ious oxid,- the removal of the arsenic from 

 solution is almost complete. Dr. Biltz offers 

 the suggestion that the action of antitoxins 

 may be susceptible of a similar explanation. 



PHOSPHORESCENT ZINC SULFID. 



Some ten years ago a description was pub- 

 lished by Henry of the preparation of a bril- 



liantly phosphorescing zinc blende which is 

 known as ' Sidot Blende.' In this prepara- 

 tion one of the essentials was that the zinc 

 used should be chemically pure. In this 

 Berichte the subject is taken up by two ob- 

 servers, who independently come to the same 

 conclusion, which is that a good preparation 

 can not be made unless traces of impurity are 

 present. The amount of this impurity should 

 be very small, Griine obtaining the best re- 

 sults when his blende contained one ten thou- 

 sandth part of copper. This blende has a 

 beautiful green phosphorescence. Silver, 

 lead, bismuth, tin, uranium or cadmium can 

 be substituted for the copper with good re- 

 sults. Hofmann finds that the best blende can 

 be prepared by adding common salt and mag- 

 nesium chlorid to a solution of the purest 

 ammonium zinc sulfate, and precipitating 

 with hydrogen sulfid. The unwashed precipi- 

 tate is then heated to a white heat for half 

 an hour. The resultant blende is composed 

 of fine crystals and phosphoresces after ex- 

 posure to the sunlight even more intensely 

 than the best 'luminous paint.' Both ob- 

 servers find that when manganese is present 

 as the impurity in the blende, the mass gives 

 an especially beautiful golden yellow phos- 

 phorescence, which is also induced by friction, 

 as is the case with some natural blendes. 

 These artificial blendes are particularly valu- 

 able for use with radium, but they have no 

 radio-activity of their own. 



PLATINUM SULFATE. 



Some time since it was announced by 

 Margules that platinum could be brought 

 into solution in sulfuric acid by the action of 

 the alternating current between platinum 

 poles. At that time the compound formed 

 could not be made to crystallize and its con- 

 stitution was doubtful. More recently, by 

 using concentrated sulfuric acid Margules 

 has obtained the compound in deep orange-red 

 crystals which are very hygroscopic and ex- 

 cessively soluble in water. These have been 

 analyzed by Stuchlik, and found to be the 

 sulfate of quadrivalent platinum of the com- 

 position, Pt(SO,)„ 4:11 JO. When the salt has 

 been completely freed from the adherent sul- 



