the Naphtha from the Bituminous Shale of Dorsetshire. Sll 



It is absolutely necessary before igniting the salts to pulverize 

 the crystals and wash them with a mixture of alcohol and aether ; 

 the appearance of the powder becomes much altered by this 

 operation, as it removes a resinous impurity which causes the 

 particles to hang together, while after washing with the mixture 

 indicated, and subsequent drying, the powder becomes as mobile 

 as fine dry sand*. Moreover, it is inadmissible to dry the cry- 

 stals by heat, a temperature of even 212° having the power to 

 cause a slow evolution of the base, and also appearing to alter the 

 constitution of the salt j it was always dried, therefore, over sul- 

 phuric acid until it ceased to lose weight. 



The second crop of crystals consisted of large thick prisms. - 



II. 3-505 grs. gave 1-115 gr. platinum. 



Per. cent. Theory (lutidine). 



31-81 31-51 



The third ; long thin square prisms. 



III. 3-507 grs. gave 1-130 gr. platinum. 



Per. cent. Theory {picoline). 



32-22 32-94 



The fourth crop ; very hard short prisms of a deep red colour. 



IV. 4-520 grs. gave 1*478 gr. platinum. 



Per, cent. Theory (picoline). 



32-69 32-94 



The fifth crop ; groups of deep orange radiated needles. 



V. 5-t52 grs. gave 1-823 gr. platinum. 



Per. cent. Theory (pyridine). 



34-71 34-60 



The first and second crops are seen therefore to be alike, also 

 the third and fourth ; the first two consisting of lutidine, the 

 next two of picoline, and the fifth of pyridine; the reason of the 

 latter base appearing only in the last crop is in consequence of 

 the smallness of the quantity present. It is interesting to ob- 

 serve the steadiness of the rise of platinum in the fractions 

 until we read the last, when it suddenly springs from 32*7 to 34-7. 

 The assertion in my former memoir that the fractional crystal- 

 lization of platinum salts affords a far readier mode of purification 

 of homologous volatile bases than distillation, appears, therefore, 

 to be borne out by this result, for it is certain that even with 

 many times the quantity of material, a separation like this could 

 not have been effected by the other method. 



It is difficult to explain how a liquid containing a considerable 

 quantity of picoline which boils at 272°, a somewhat less amount 

 of lutidine (boiling-point 310°), and a little pyridine boiling at 

 240°, should distil below 210° (especially as it was ascertained 



* It is beheved that Hofmann first indicated the importance of this pro- 

 cedure in his researches on the volatile organic bases. 



P2 



