Febbuary 7, 1908] 



SCIENCE 



239 



supervises from the Washington office the 

 work in the Middle Atlantic States. Other 

 engineers present were C. C. Covert and F. 

 W. Henshaw, of the Washington office, recent- 

 ly engaged in stream measurements in Alaska 

 in cooperation with the survey's Division of 

 Alaskan Mineral Eesources; E. H. Bolster 

 and W. G. Steward, also of the home office; 

 F. W. Hanna, of the U. S. Reclamation Serv- 

 ice; and Sydney K. Clapp, of the Board of 

 Additional Water Supply for New York City. 

 The meeting was presided over by the chief 

 hydrographer, Mr. Marshall O. Leighton. The 

 subjects under discussion included methods of 

 work, instruments and equipment, scientific 

 studies, storage and evaporation investiga- 

 tions, cost-keeping systems, and publicity and 

 cooperation work. Special addresses were 

 made by the director of the survey, George 

 Otis Smith, and by Dr. G. K. Gilbert, who 

 explained in detail the methods of investiga- 

 tion of what is known as the " debris problem " 

 of California rivers, now in progress at the 

 hydrolog-ic laboratory of the' survey, at Berke- 

 ley, Cal. 



The London Times states that in a recent 

 German patent a method is described for pro- 

 ducing artificially certain mineral species, 

 such as olivine, zircon, beryll, and spinelle, in 

 a definitely crystalline form. This consists 

 in dissolving their constituent oxides in appro- 

 priate proportions in molten sodium or potas- 

 sium metaborate. The temperature of the 

 fused mixture is then raised to 1,300° C, 

 when the alkali metaborate volatilizes, leav- 

 ing the artificial mineral in the form of 

 crystals. In addition to obtaining products 

 corresponding with the naturally occurring 

 minerals, other compounds having no minera- 

 logical counterparts may be produced by this 

 method. A nickel chrome spinelle, NiO, 

 Cr^Oj, prepared from its constituent oxides, 

 was' obtained in the form of small green 

 crystals. It is well known that the mineral 

 species corundimi occurs in the form of very 

 variously colored stones ranging from color- 

 less sapphire to brown and opaque corundum. 

 Between these extremes one meets with sap- 

 phires tinted in yellow, green, blue, red, and 

 intermediate hues, and it is generally supposed 



that these various colors are due to the pres- 

 ence of compounds of iron, manganese, chro- 

 mium, titanium, or other foreign elements. In 

 the Compies rendus de I'Academie des Sci- 

 ences F. Bordas describes experiments in 

 which the color of these gems is caused to 

 change by exposing the stones to the action of 

 a very radioactive specimen of radium bro- 

 mide. In these circumstances a blue sapphire 

 assumes successively green, light yellow, and 

 dark yellow tints, whilst a red sapphire de- 

 velops in succession shades of violet, blue, 

 green and yellow. These experiments justify 

 the belief that the distinctive colors of these 

 precious stones are not due to the presence of 

 any particular oxides. The variation always 

 occurs in the above sense from red to yellow, 

 and it seems likely that the topaz represents 

 the last term in this transformation. More- 

 over it seems probable that these gems are 

 found in regions where the surrounding soil 

 has a certain degree of radioactivity. This 

 idea receives support from the fact that the 

 yellow sapphires are the commonest, although 

 yellow and blue sapphires frequently occur 

 together. The gems which have been thus 

 artificially colored are not radioactive ; they do 

 not become luminescent in the dark under the 

 influence of radium bromide, but they retain 

 their color on heating. 



Nature states that an addition to the exliibi- 

 tion galleries of the British Museum (Natural 

 History) has been made in the shape of a copy 

 of a water-color drawing made about 1585 by 

 John White, containing the earliest known 

 representation of the American king-crab, 

 Limulus polyphemus. John White, who was 

 one of the first settlers in Virginia, of which 

 he was for some time governor, served as lieu- 

 tenant to Sir Walter Raleigh. In three vol- 

 umes of drawings by him preserved in the 

 department of prints and drawings in the 

 British Museum, many of the delineations of 

 natural objects are of great beauty, and show 

 a fidelity to nature rare at the period. The 

 drawing in which the king-crab is depicted 

 was engraved, with some modifications, for 

 de Bry's " America " (" Grands Voyages," 

 Part I., pi. 13) in 1690. In the engraving 

 the king-crab is, however, shown in somewhat 



