TRANSACTIONS OF THE SECTIONS. 57 



On neutralizing a portion with ammonia, and testing with nitrate 

 of silver, a yellow precipitate of phosphate of silver was thrown down. 

 A further examination showed the presence of sulphuric acid, and 

 traces of hydrochloric acid. 



Finding phosphoric acid in this result of aqueous distillation, at a 

 moderate heat, the author suggested the possibility of its causing a 

 fallacy in the above mode of testing for fluorine, as it is well known that 

 glass of inferior quality will be corroded by the vapour of phosphoric 

 acid, and all the animal substances in which fluorine has been said to 

 exist, are particularly rich in phosphoric acid. 



Having failed to detect fluorine in bone, Dr. Rees determined on 

 testing for it in the enamel of teeth, in recent ivory, and in the preci- 

 pitate obtained from the urine by means of lime-water. Two different 

 specimens of ivory gave no evidence of the presence of fluoric acid, 

 when carefully tested both before and after calcination ; and the author 

 was equally unsuccessful with the enamel of teeth and the precipitate 

 obtained from the urine by lime-water. 



" In these experiments, when there was no action upon the glass, it 

 was always found that the addition of 0'3 gr. of fluoride of calcium 

 produced a strong and indelible stain." 



Dr. Rees observes in conclusion, " I must express my firm convic- 

 tion, that if fluoride of calcium be an ingredient of fossil ivory^ it must 

 be regarded as an extraneous matter introduced during mineralization ; 

 and that no such constituent exists in recent ivory, the enamel of teeth, 

 human bones or urine. 



" Since writing the above, I have had an opportunity of experiment- 

 ing on a specimen of fossil ivory, and have succeeded in obtaining 

 evidence of the presence of fluorine. I could not however ascertain 

 the locality from which this specimen was procured. When digested 

 with strong sulphuric acid, at a gentle heat, it produced a rapid and 

 indelible stain on the plate of glass used for the experiment. 



Description of an Apparatus for the Analysis of Organic Substances. 

 By Prof. Hess, of St. Petersburgh. 



The author proposed a modification of Prof. Liebig's apparatus, for 

 the analysis of organic substances, and stated it to be particularly useful 

 in the decomposition of substances which are susceptible of but slow 

 combustion, — of resins, fatty substances, liquids not very volatile, and 

 particularly of solid bodies. The only difierence in the mode of con- 

 ducting the analysis from that adopted by Liebig is the attachment at 

 both ends of the tube for combustion of a caustic potash apparatus, 

 and at one end of a gas-holder containing oxygen, upon the prin- 

 ciple originally introduced by Dr. Prout. A description of the appa- 

 ratus has been published in the Bulletin Scientijique, of St. Petersburgh, 

 accompanied by a figure. The heat is communicated by means of a 

 lamp, described and figured by Prof. Hess, in Liebig's Annalen der 

 Pharmacic for 1838. 



