134 Royal Society : — 



those which are alone appropriate to the problem, and it evolves 

 both the periodic and the secular inequalities by the same process. 

 Terms containing ent as a factor, which are met with in other solu- 

 tions of the same problem, do not occur in this method ; but there 

 are terms containing the factor e'nt, which are shown to be convert- 

 ible into periodic functions, and to have reference to secular varia- 

 tions of the eccentricity and of the motion of the apse. The paper 

 concludes with some general remarks on the principle of this approxi- 

 mate solution of the problem of three bodies, and an explanation of 

 the analytical circumstances which make it, in common with the 

 method 'of the variation of parameters, proper for determining 

 directly the motion of the apses of an orbit. 



"On some of the Products of the Distillation of Boghead Coal at 

 low temperatures." By C. Greville Williams, Esq. 



In presenting a brief preliminary notice of an investigation of the 

 substances obtained by distilling boghead coal at low temperatures, I 

 may observe that I was induced to undertake it from remarking the 

 low density of the naphtha produced in the process ; it being only 

 •750 at 60° F., although its boiling-point, previous to the rectifica- 

 tions, was as high as 290° F. 



After fifteen complete fractionations of the portion distilling below 

 310° F., boiUng-points were obtained as low as 170°, and it was 

 found that the fluid could be separated, by careful treatment with 

 fuming nitric, or a mixture of nitric and sulphuric acids, into two 

 bodies, one forming a nitro-compouud, the other being unacted on. 

 The latter was washed several times with a strong alkaline solution, 

 and, after being digested for a few days with sticks of potash to 

 remove adherent moisture, rectified over sodium. In this manner I 

 obtained a colourless and very mobile fluid with a pleasant odour, 

 distantly resembling that of hawthorn blossoms. Its density at 60° 

 was '725. 



I selected the fraction boiling in the fifteenth rectification at 

 240° F. to make a preliminary experiment upon, and, after purifica- 

 tion in the manner described, it gave in three perfectly concordant 

 analyses, exactly the per-centage of carbon and hydrogen required 

 for butyle (valy'le of Kolbe), the radical of the butylic alcohol. Two 

 determinations of the vapour density, taken respectively at 80° and 

 107° above its boiling-point, gave numbers closely coinciding with 

 theory. 



When it is considered that 68° or more of difference of boiling- 

 point only cause a variation of 0'3 in the per-centage of carbon and 

 hydrogen of bodies of this class, it becomes evident that if I had 

 taken the fraction boiling at 223° (Wurtz) or 226° (Kolbe), it would 

 have yielded the same results. This point is now under examination. 

 The formula 



corresponds not oily to butyle, but also to the hydruret of caprylyle, 

 and, of course, both these bodies have the same vapour density ; but 

 several circumstances lead me to beheve the hydrocarbon I have 



