July 29, 1898.] 



SCIENCE. 



119 



althongh in respect to specific heat each 

 element in a solid seems to be independent 

 of the other elements with which it is asso- 

 ciated, when the elementary substances are 

 vaporized some rise in separate atoms like 

 mercury, some in groups of atoms like 

 iodine, sulphur, arsenic and phosphorus, 

 and as the temperature is raised these 

 groups are simplified with very varying de- 

 grees of readiness. 



The two metals, cobalt and nickel, with 

 which I began my inquiry, have very nearly 

 the same atomic weight, the value, 58.24 

 for nickel and that for cobalt 58.49, being 

 calculated by F. W. Clarke from the results 

 of a great many analyses by many different 

 chemists. They are so close together that 

 for a long time they were regarded as iden- 

 tical, and Mendeleef does not hesitate even 

 to invert the order by making Co ^58.5 

 and Ni =: 59. These metals, nevertheless, 

 differ from each other in several very im- 

 portant chemical characters. Nickel, for 

 example, forms the well known and highly 

 remarkable compound with carbonic oxide 

 discovered by Dr. Mond. Cobalt, on the 

 other hand, produces many ammino-com- 

 pounds to which there is nothing corre- 

 sponding among the compounds of nickel. 



Having put aside the common excuses 

 for the observed divergences from the con- 

 stant of Dulong and Petit, we are com- 

 pelled to look round for some other 

 hypothesis to explain them. 



The constitution of carbon compounds is 

 now accounted for by a hypothesis concern- 

 ing the configuration of the carbon atom in- 

 troduced by Van't Hofif and LeBel twenty- 

 five years ago, and which is now accepted by 

 the whole chemical world. It seems not un- 

 reasonable to apply a similar idea to the ex- 

 planation of those cases of isomerism which 

 have been observed in certain compounds 

 of the metals, notably chromium, cobalt 

 -and platinum. This has already been done 

 by Professor Werner, of Zurich. If the 



constitution of compounds can be safely 

 explained by such hypothesis, this implies 

 the assumption of peculiarities in the con- 

 figuration of the individual constituent 

 metals around which the various radicles 

 are grouped in such compounds; and hence 

 peculiarities in the behavior of such metals 

 in the elemental form may possibly be ac- 

 counted for. For the atom of cobalt Pro- 

 fessor Werner employs the figure of the 

 regular octahedron. For nickel, therefore, 

 which differs from cobalt in many ways, a 

 different figure must be chosen. This, 

 however, is for the present a matter of pure 

 speculation. 



PRELIMINARY NOTE ON THE GROWTH OF 

 PLANTS IN OYPSUM. 

 In the ' Handbook of Experiment Station 

 Work ' (1893), p. 176, the following passage 

 occurs : 



" The action of gypsum as a fertilizer is 

 not well understood. It appears to act in- 

 directly in the soil, setting free plant food, 

 especially potash, already present, but con- 

 tributing little directly to the support of 

 plants * * * It also promotes nitrification. 

 Gypsum is used as an absorbent in manure 

 heaps to prevent loss of ammonia. " 



Nevertheless, plants will grow in nearly 

 pure gypsum, as we propose to show. 



On the east side of the San Andreas 

 mountains, in southern New Mexico, is an 

 immense deposit of white sand, which has 

 the following composition, according to 

 data kindly furnished by Mr, R. F. Hare, 

 assistant chemist of the New Mexico Ex- 

 periment Station : 



CaSOi + 2 HoO (Gypsum) 97.00 per cent. 



CaCOs (Calcium Carbonate) 2.86 " " 



MgCOj (Magnesium Carbonate)... .06 " " 



MgSOj (Magnesium Sulphate) 12 " " 



K2SO4 07 " " 



NajCOj trace. 



NaCl trace. 



In this deposit, locally known as the 



