. i:«;v?>wMr. Soane on the Geometry o/Boethius. 529 



and I have lately given an account of a set of experiments on the 

 combustion of potassium, tin, antimony, mercury, phosphorus and 

 copper in chlorine gas. So far as I am aware, the only other expe- 

 riments on this subject are those described by M. Abria on the com- 

 bustion of hydrogen and phosphorus in chlorine. From a com- 

 parison of the results, it appears that in several cases the quantities 

 of heat evolved during the combustion of the same metal in oxygen 

 and chlorine are nearly the same. This observation applies parti- 

 cularly to the cases of iron, tin and antimony. Zinc however dis- 

 engages a greater quantity of heat with chlorine (6309 units) than 

 with oxygen (5366 units), and copper nearly twice as much (3805 

 and 2394 units). Phosphorus, on the contrary, gives less heat with 

 chlorine than with oxygen (2683 and 4509 units). On comparing 

 the quantities of heat disengaged by different bodies in combining 

 with the same volume of chlorine, it will be found that potassium 

 disengages a larger amount of heat than any other body hitherto 

 examined, twice as much as zinc, and nearly four times as much as 

 tin, antimony or copper. 



Combinations of Bromine and Iodine. — The heat disengaged by 

 the same body in combining with bromine is less than with chlorine, 

 and with iodine less than with bromine. The greater development 

 of heat in the case of chlorine is at least partly due to that element 

 being in the gaseous state before combination. In some early expe- 

 riments, I observed that the quantities of heat developed on con- 

 verting equivalent solutions of the sesquichloride, sesquibromide 

 and sesquiiodide of iron into the corresponding proto-compounds 

 were equal. When a solution of protochloride of iron is converted 

 into sesquichloride by agitation with chlorine gas, a definite disen- 

 gagement of heat occurs, as also in the formation of the sesquibro- 

 mide of iron by the combination of the protobromide and bromine ; 

 but in the corresponding reaction between the protoiodide of iron 

 and iodine, no change of temperature can be observed. 



LX V. On the Connexion of Pope Gerbert with the Geometry 

 of Boethius. By George Sloane, Esq.* 



IN the editions of Boethius's collective works we find a translation 

 of the first four books of Euclid, or rather of the propositions or 

 enunciations alone. This treatise is divided into two books, both of 

 ■which purport to be a translation of Euclid, although in fact the 

 first only is such, the second being for the most part a collection of. 

 problems in mensurationf. '^/^ 



* We avail ourselves of the permission of the Philological Society to transfer tliis 

 Paper to our pages from the Journal of their Proceedings, now extending to four 

 very interesting Volumes : we are also indebted to the Author for the additions and 

 corrections witii whicli he has favoured us. 



t T. ii. p. 1187-154C. ed. Basil, 1570. Except in one or two instances, which 

 will be readily distinguished, the references in this paper arc to the pages and lines 

 of the new edition of the Agrimensors, ' Gromatici Veteres ex recens. C. Lach- 

 manui,' Berol., I848ri.v)iu {;^iu 



