790 



SCIENCE. 



[N. S. Vol. XVIII. No. 468. 



triphane, a yellowish-green spodumene, which 

 exhibits pink fluorescence in blue light; em- 

 erald, which shows crimson fluorescence in the 

 upper part of the spectrum, and diamond, with 

 greenish-blue to blue fluorescence excited by 

 several kinds of energy but more or less 

 masked in ordinary light. 



In fluorescent substances excitation pro- 

 duces a certain opalescence or milkiness 

 which is sometimes of sufficient strength to be 

 of importance. It can not be taken as an 

 indication of impurities in the materials. In 

 the white diamond such a phenomenon is a 

 detrimental quality. 



Fluorescence affords a simple and positive 

 method of distinguishing some of the fluores- 

 cent gems from imitations. Glass is not 

 fluorescent and hence is easily detected. 

 Other compositions when fluorescent show dif- 

 ferent colors from the genuine stones. In 

 doublets the cement appears as an opaque film 

 and the components differ in behavior. Arti- 

 ficial pearls of high grade have not been ex- 

 amined, but probably they will behave like 

 the genuine. Artificial, or ' regenerated,' ruby 

 has been examined in a single specimen. It 

 acts like the natural stone in blue light, while 

 with the air-gap spark between iron or alum- 

 inum electrodes it has a brighter color than 

 any of the several natural rubies which were 

 examined. 



The following gems were stated to be non- 

 fluorescent : Garnet, amethyst, Spanish topaz, 

 yellow Brazilian topaz, sapphire, ordinary 

 beryl, possibly Siamese ruby. 



In the discussion of Mr. Levison's paper 

 Professor Kemp expressed the hope that there 

 would be a practical outcome from such inves- 

 tigations which would enable those not experts 

 to detect false or artificial gems; Mr. Kunz 

 said that there were simpler ways than the 

 use of fluorescence for the determination of 

 gems, and Professor D. S. Martin emphasized 

 the desirability of getting definite information 

 as to the wave-lengths to which gems respond. 



The third paper of the evening was ' Min- 

 eralogical Notes,' by Dr. George P. Kunz, in 

 the course of which the author exhibited white 

 compact garnet from Fresno County, Cali- 

 fornia, associated with the newly described 



compact vesuvianite, or ' californite.' In con- 

 nection with, these two compact minerals at- 

 tention was called to the third compact min- 

 eral ' pectolite,' which was described some 

 years ago by W. P. Blake. Pyroelectric zinc 

 blende associated with wollastonite from Mari- 

 posa County, California, also was exhibited. 

 Edmund Otis Hovey, 



Secretary. 



THE TORREY BOTANICAL CLUB. 



The club met at the Botanical Garden on 

 November 25. 



Dr. Britton read a memorial on the life 

 work of the late Mr. Cornelius Van Brunt. 

 It was ordered spread on the minutes and 

 printed in Torreya as part of the proceedings. 



The principal paper on the scientific pro- 

 gram was by Mrs. Britton, entitled ' Notes 

 on Further Botanical Explorations in Cuba.' 

 The party consisting of Dr. and Mrs. Britton 

 and Mr. Percy Wilson went to Cuba by way 

 of Tampa, Florida, going direct to Matanzas, 

 which point was reached on August 27. Ex- 

 tracts were read from her diary giving an 

 interesting account of the daily happenings 

 during the exploration of the region about 

 Matanzas, Cardenas and Sagua. Many pho- 

 tographs were shown illustrating the regions 

 visited, and specimens of some of the more 

 conspicuous plants were exhibited. As the 

 herbarium material secured by the expedition 

 has not yet been studied, no detailed account 

 of the botanical features of the region was 

 attempted. All of this part of the island has 

 been devastated by war. There is no primi- 

 tive forest, and comparatively few large trees 

 are left standing. On the return a few days 

 were spent in Havana, visiting the botanical 

 institutions of that city. 



Dr. Britton exhibited specimens of what 

 seem to be two species of hackberry. The 

 common Celtis Occident alls of the eastern 

 states is a small tree seldom exceeding forty 

 feet, having smooth, slightly acuminate leaves 

 and globular orange-colored fruits. On an 

 excursion of the Torrey Club to the Delaware 

 Water Gap some years ago, some much larger 

 trees were observed growing in moist locations 

 and having long acuminate leaves and oval 



