April 21, 1905.] 



SCIENCE. 



629 



deeplj' shaded shelf under a remarkable rock 

 overhang on the Cave Cays of the Exuma 

 Chain furnished some of the most interesting 

 algas obtained on the recent expedition. The 

 so-called creeks constitute good collecting 

 grounds, especially if well exposed to tidal 

 currents, and the roots of the red mangrove, 

 which commonly borders such, always harbor 

 algae of interest, particularly when standing 

 in water that is three feet or more deep at low 

 tide. Nearly all the larger islands have brack- 

 ish ponds which have a peculiar flora varying 

 in character with the salinity of the water. 

 Hundreds of square miles in the Bahaman 

 region are occupied by the ' banks,' on which 

 the water is very shallow, mostly from five to 

 twenty feet deep ; these banks often consist of 

 clean white sand with little visible organic 

 life, yet in many places are found, more or 

 less abundantly, representatives of such gen- 

 era as Penicillus, Rhipocephalus and Udotea, 

 growing directly out of the sand, and Micro- 

 dictyon, Gymnosorus, W urdemannia, Lawr- 

 encia, Chondria, H erposiphonia and others, 

 attached to sponges, corals, sea-fans, etc. In 

 the winter and spring months, at least, very 

 little is found washed ashore except species of 

 Sargassum and their epiphytes. 



The speaker remarked upon the desirability 

 of extensive dredging operations in order to 

 complete our knowledge of the marine flora of 

 the Bahaman archipelago. A few character- 

 istic specimens of, Bahaman marine algae were 

 exhibited. Special attention was directed to 

 four species of Penicillus, viz., P. capitatus, 

 dumetosus, Lamourouxii and the recently de- 

 scribed Penicillus pyriformis. 



Rhipocephalus Phoenix and ohlongus and 

 various species of Udotea, Avrainvillea and 

 Halimeda were also discussed. 



Mrs. Britton, who accompanied the expedi- 

 tion, spoke more particularly of the flora of 

 the island of New Providence, where she spent 

 the time collecting while the other members 

 of the party were cruising. Several exceed- 

 ingly fine photographs of the local scenery 

 were exhibited. 



Edward W. Berry, 



Seci'etary. 



THE CHEMICAL SOCIETY OF WASHINGTON. 



The 156th regular meeting was held Febru- 

 ary 9, 1905, in the chemical lecture hall of 

 the George Washington University. Pro- 

 fessor W. R. Whitney, of the research labora- 

 tory of the General Electric Company, deliv- 

 ered an experimental lecture upon the subject, 

 ' Colloids.' 



The 157th regular meeting was held March 

 9, 1905, in the assembly hall of the Cosmos 

 Club. 



The first paper on the program was deliv- 

 ered by Mr. W. L. Dubois, and entitled ' Notes 

 on Sulphur Determination.' 



For the determination of sulphur in foods 

 and feces a modification of Newmann's meth- 

 od, consisting of burning the sample with 

 sodium peroxid and sodium carbonate, has 

 been substituted for Osborne's method in the 

 Bureau of Chemistry. The new method pos- 

 sesses these advantages : (1) combustion is 

 more satisfactory, cases of incomplete burning 

 being rare; (2) many more samples can be 

 handled, owing to greater ease of manipula- 

 tion; (3) economy of sodium peroxid. 



The most satisfactory lamp tried at the 

 Bureau of Chemistry is Barthel's alcohol 

 burner, which may be adjusted from a very 

 low flame to a powerful blast. 



The second paper was entitled ' The Grig- 

 nard Reaction,' and was presented by Dr. C. 

 E. Waters. 



This is one of the most valuable methods of 

 organic synthesis that has been devised re- 

 cently. An organic halide, RX, dissolved in 

 ether, is allowed to act upon magnesium turn- 

 ings, which dissolve, forming a clear solution 

 of RMgX. This solution gives addition-prod- 

 ucts with aldehydes, ketones, esters, ketone- 

 and hydroxy-acids, with sulphur, selenium, 

 oxygen, carbon dioxide and oxychloride, cy- 

 anogen, oxides of nitrogen, ajid other classes 

 of compounds. When these addition-products 

 are treated with water or dilute acids a num- 

 ber of different classes of products are ob- 

 tained. By this method we can get primary, 

 secondary and tertiary alcohols, ketones, hy- 

 droxy-acids, thio- and seleno-compounds, hy- 

 droxylamine derivatives, etc. With metallic 



