CHEMICAL SCIENCE. 231 



It is based partially on the greater affinity of bromine for the metals, and 

 partially on the violet color which iodine communicates to the sulphuret of 

 carbon. The matter is treated with potash (or carbonate of potash, which 

 may be more easily obtained pure and free from chlorine) ; it is evaporated 

 and calcined to transform the bromate into bromid ; it is then neutralized by 

 means of an acid ; the liquid is put into a test tube, and a drop of sulphuret 

 of carbon is introduced, after which a drop or two of bromine, dissolved in 

 distilled water, is added; it is then agitated, and if there is iodine present, 

 the sulphuret of cobalt is colored violet. It is colored yellow by bromine. 

 It is important to avoid an excess of bromine, lest it form a bromid of iodine, 

 which does not act. I have tried the process, and found it exact nearly to a 

 tenth of a milligram of iodine. Nickks's Correspondence, SiUimari's Journal 



ISOLATION OF FLUORINE. 



M. Frerny, of France, has continued his investigations during the past 

 year on the isolation of fluorine. By causing a powerful galvanic current to 

 act upon fused fluoride of potassium, an odorous gas was generated, which, 

 on disengagement from the mouth of the retort, decomposed water, producing 

 hydrofluoric acid. This gas, there is every reason to believe, was fluorine. 



FLUORINE IX THE SCALES OF FISHES. 



At a recent meeting of the Boston Society of Natural History, Dr. C. T. 

 Jackson communicated some chemical researches which he had recently made 

 on the composition of the scales of the gar-pike. He stated that he had dis- 

 covered fluorine as one of their components, and had etched glass with the 

 fluo-hydric acid, eliminated from the ashes of the scales by the action of sul- 

 phuric acid. The analysis was yet incomplete, but he would state that the 

 scales contain 45.2 per cent, of animal matter, destructible by heat, and that 

 the mineral matters consist of phosphate of lime, fluoride of calcium, and 

 phosphate of magnesia, with some carbonate of lime. The proportion of lime, 

 in 100 grains of the ashes, was 45.1 per cent., and of magnesia 8.8 per cent., 

 while the phosphoric acid, already separated in this preliminary or qualitative 

 analysis, was 29.96 per cent. 



Dr. Jackson remarked that the search for fluorine was suggested by an 

 idea communicated to him by M. C. Girard, that the scales of fishes were 

 "supposed to be anatomically homologous with the enamel of teeth," an idea 

 that now is sustained by chemical analogy. 



ON THE PRODUCTION OF BORACIC ACID AND AMMONIA BY 

 YOLCANIC ACTION. BY ROBERT WARRINGTON, F.C.S. 



The simultaneous occurrence of boracic acid and ammonia in the neighbor- 

 hood of volcanoes has been frequently observed, and its cause has given rise 

 to a good deal of speculation, although no very definite conclusions have as 

 yet been arrived at. Some information and specimens received from the Island 



