278 Dr. J. L. W. Thudichurn. [Mar. 18. 



very slow when the satellite is far from the planet ; this must indeed 

 obviously be the case, because the tidal effects vary as the inverse sixth 

 power of the satellite's mean distance. 



V. " On the Modifications of the Spectrum of Potassium which 

 are Effected by the Presence of Phosphoric Acid, and on 

 the Inorganic Bases and Salts which are found in combina- 

 tion with Educts of the Brain." By J. L. W. THUDICHUM, 

 M.D., F.R.C.P.L. Communicated by John Simon, C.B., 

 F.R.S., &c. Received March 10, 1880. 



Among the results of a large investigation on which I have for 

 many years been engaged in regard of the chemistry of the brain, I 

 had been led to conclude that the so-called "protagon" of Oscar 

 Liebreich is not a definite chemical body, but is a variable mixture of 

 several bodies. This conclusion of mine (which agrees .with opinions 

 expressed on the same subject by Strecker, Diaconow, and Hoppe- 

 Seyler) was published by me in 1874,* and endeavours to controvert 

 it have since then been made, on several occasions, by Dr. Arthur 

 Gramgee.t Last summer, he brought before the Royal Society^ his 

 contentions for the chemical individuality of "protagon"; and it 

 fortunately was in my power shortly afterwards to publish evidence, 

 which, I believe, those who will take the trouble to follow it will 

 find quite unanswerable, that Dr. Gramgee's contentions were mis- 

 taken^ Part of my evidence to that effect consisted in showing by 

 quantitative analyses that Dr. Gramgee's so-called "protagon" con- 

 tains 0"7 per cent, of potassium ; secondly, that in connexion with 

 trifling differences in the extraction process, the proportion of potas- 

 sium in different specimens of " protagon " can be made to range 

 from a trace to 1*6 per cent. ; thirdly, that with the variable quantities 

 of potassium the quantities of phosphorus and other ingredients will 

 also vary. 



In the "last published number, No. 200, p. Ill, of the " Proceedings 

 of the Royal Society," I find that Dr. Gamgee has recently brought 

 the question again under notice of the Society, and that, in doing so, 

 he especially rests his case upon the following statement made by his 

 colleague, Professor Roscoe, on the subject of some examinations, 



* " Reports of the Medical Officer of the Privy Council and Local Government 

 Board." New Series. No. III. 



t " Zeitschrift fur Physiol. Chemie," vol. hi, p. 260 ; " Ber. Deutsch. Chem. 

 G-es.," 1879, &c. 



X "Proc. Roy. Soc," vol. xxix, p. 151. 



§ " Annals of Chemical Medicine." Edited by J. L. W. Thudichum. Yol. i, 

 p. 254. 



