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 combination with educts of the brain

Abstract

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 HoppeSeyler) was published by me in 1874, and endeavours to controvert it have since then been made, on several occasions, by Dr. Arthur Gamgee. 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. Gamgee’s contentions were mistaken.§ Part of my evidence to that effect consisted in showing by quantitative analyses that Dr. Gamgee’s so-called “ protagon” contains 0·7 per cent, of potassium; secondly, that in connexion with trifling differences in the extraction process, the proportion of potassium 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. 111, 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, which, at Dr. Gamgee’s request, he had made for him: see “ Proceedings,” vol. xxx, p. 113:—“I have examined spectroscopically for potash a sample of protagon furnished me by Dr. Gamgee, and labelled ‘Protagon, twice recrystallised, Blankenhom.’ I could not detect any potash by the spectroscope in the incinerated mass from 0·1 grm. of substance. With the carbonised mass obtained from 1·0 grm. of substance I obtained the potasssium line ( α ) very faintly, and from comparative experiments with a dilute solution of a potassium salt I estimate the quantity of potash in 1 grm. of the substance Lot to exceed 1/20 mgrm. The carbonised residue of 1 grm. of protagon was carefully oxidised with pure nitric acid, when a small quantity of fused metaphosphoric acid remained after ignition. The residue weighed 0·0278 grm., corresponding to 1·08 per cent, of phosphorus.— (Signed) H. E. Roscoe.”