OCTOBKK 28, 1898.] 



SCIENCE. 



587 



laborious process, which gives rise to beauti- 

 ful crystals with a coppery red sheen, and 

 which are a very complex oxalate. Under 

 certain circumstances the pale yellow crys- 

 tals of the normal platoxalate are obtained. 

 Vezes finds that when the chlorplatinite 

 of potassium is heated with neutral potas- 

 sium oxalate in a neutral solution the pla- 

 toxalate of potassium is very readily formed 

 with no admixture of more complex com- 

 pounds. An analogous reaction produces 

 the normal palladoxalates. 



A PRACTICAL application of this reaction 

 is made in Vezes' second paper. With the 

 exception of chlorplatinic acid, potassium 

 chlorplatinite is doubtless the most used 

 platinum compound, being the starting point 

 for all the platinum- ammonium bases. Up to 

 this time no method of its manufacture can 

 be considered satisfactory, especially upon 

 a commercial scale. The reduction of 

 chlorplatinic acid by sulfur dioxid must 

 be very carefully carried out or complex 

 sulfoplatinites result ; heating platinic chlo- 

 rid till two atoms of chlorin are given 

 off is difficult to accomplish with anything 

 like quantitative precision ; and the re- 

 duction with cuprous chlorid gives a prod- 

 uct very difficult to free from all traces of 

 copper. Vezes suggests the use of oxalic 

 acid in neutral solution. If potassium chlor- 

 platinate (and most platinum residues are 

 of this compound) is boiled with the theo- 

 retical quantity — 37% — of neutral potas- 

 sium oxalate in water insuificient to dissolve 

 the platinum salt, in the course of several 

 hours it is quantitatively converted into 

 the chlorplatinite, most of which crystal- 

 lizes out on cooling and all of which may 

 be recovered by adding alcohol. This opera- 

 tion can be successfully carried out on a 

 large scale. Since the publication of Vezes' 

 article the method has been tested in the 

 Washington and Lee University laboratory, 

 and I can bear testimony to its success 



and its great advantage over the earlier 

 methods. 



Vezes' third paper is on the criticism of 

 Dumas on Stas' determination of the atomic 

 mass of nitrogen. Dumas showed the pres- 

 ence of oxj'gen in silver which has been 

 fused, and calculated that the figure of Stas 

 should be reduced from 14.044 to 14.002, a 

 variation greater than that of experimental 

 error. Vezes has gone over the calcula- 

 tions, using Stas' original figures and in- 

 troducing the correction for occluded oxy- 

 gen, and shows that the original figure of 

 Stas would be reduced from 14.044 only to 

 14.040, a change far less than the limit of 

 experimental error. Another testimony is 

 thus borne to the wonderfully accurate work 

 of the Belgian chemist. 



J. L. H. 



BOTANICAL NOTES. 

 A STUDY OF TOADSTOOLS. 



Mr. C. G-. Lloyd, of Cincinnati, an en- 

 thusiastic student of the larger fungi has' 

 recently brought out an illustrated paper 

 ('A Compilation of the Volvte of the United 

 States ') which deals with the species of 

 two genera of toadstools, viz.: Amanita, 

 with thirty-eight species, and Volvaria, with 

 twelve. Nine ' half tone ' reproductions 

 of photographs illustrate the paper. These 

 toadstools are characterized by the young, 

 plants being enclosed in a thick membrane,, 

 called a volva, and having a soft and fleshy 

 structure, with entire, thin, sharp gills,- 

 which do not deliquesce. Some of the 

 species are edible, but so many are poisonous- 

 that the author says: " My advice is, Don't 

 eat any Amanitas, and you will make no- 

 mistake." 



A SOUTHERN FERN FAR FROM HOME. 



Foe some time rumors of the occurrence 

 of the Southern Maidenhair Fern {Adiantum 

 capillus-veneris) in the Black Hills of south- 

 western South Dakota have drifted to the 

 Botanical Department of the University of 



