2.20 



Prof. Roscoe on Vanadium, 



[Dec. 19, 



cliolopliseine and biliverdine have shown that they have no apparent rela- 

 tion to hematine, as v^^as formerly supposed, the analyses of uromelanine 

 have made it probable that this substance is a derivative of the coloured part 

 of the blood, cruorine or hematocrystalline, not, however, of hematine, 

 for the atomic weight of hematine is apparently smaller than that of uro- 

 melanine. But crystallized cruorine has an atomic weight of about 13,000 

 (Fe = 0'45 per cent.). From suchabody urochrome, including as it does 

 uromelanine, uropittine, omicholine, and perhaps other matters (to be 

 described in future communications), might be derived with an atomic 

 weight of perhaps 1500, being itself near that of albumen (1612), but 

 unable to derive fi'om it. The author thinks it possible that the quantity 

 of blood-disintegration might be measured by determining the amount of 

 uromelanine obtainable from given quantities of urine excreted in given times. 

 In any case uromelanine is one of the most remarkable substances in the 

 whole domain of organic and animal chemistry, and the further study of 

 its metamorphoses cannot fail to jdeld highly interesting results. 



December 19, 1867. 

 Lieut. -General SABINE, President, in the Chair. 



Pursuant to notice given at the last Meeting, Professor Stokes proposed, 

 and Mr. De la Rue seconded, the Right Honourable the Earl of Rosse for 

 election and immediate ballot. 



The ballot having been taken, the Earl of Rosse was declared duly 

 elected. 



The Bakerian Lecture, " Researches on Vanadium," was delivered by 

 Prof. H. E. Roscoe, Ph.D., F.R.S. 



The Bakerian Lecture. — "Researches onVanadium.^^ — Parti. By 

 Henry E. Roscoe, B.A.,E.R.S. Recei/ed November 20, 1867. 



(Abstract.) 



I. Introduction. 



Amongst the physical properties which point out the general relation- 

 ship and classification of chemical compounds, none has so deservedly ob- 

 tained the confidence of chemists as isomorphism. The vanadium com- 

 pounds have, however, proved a remarkable and unexplained exception to 

 the conclusions which generally follow^ from well ascertained identity of 

 crystalline form. Rammelsberg, and afterwards, more completel}'', Schabus, 

 pointed out the fact that the mineral vanadinite from several localities (a 

 compound of lead vanadate and lead chloride) is isomorphous with apatite, 

 pyromorphite, and mimetesite, minerals consisting of calcium phosphato- 

 chloride, lead pliosphato-chloride, and lead arsenato-chloride. 



The crystalline form of all these minerals is an hexagonal prism, termi- 

 nated by 6-sided pyramids. So far indeed has the isomorphism of these 



