Proceedings of the British Association. 95 



differ from the times at Leith, in which the mean temperature is 48°, 

 and the lat. about 55° N. At the Frankfort Arsenal, the line of mean 

 temperature is crossed also about 10 a.m., but differed at night, being 

 between 7 and 8 p.m. ; whilst at Plymouth, the line of mean temperature 

 was crossed soon after 8 a.m., and 7 a.m. by the latest observations. The 

 little comparative mean range of the thermometer at Leith and Kandy, 

 and in Ceylon, gave great similarity to the curves indicating the march of 

 the hourly tempei'ature in these places. — The author concluded with 

 some general remarks on this subject. 



Prof. Forbes and Prof. Whewell pointed out the necessity of reduc- 

 ing the observations to 32° of Fah. — Mr. Harris stated, that the tem- 

 peratures at which the observations were made had not greatly differed, 

 but that, before the Report appeared, the observations should be re- 

 vised and reduced. 



' On a New Calorimeter, by which the Heat disengaged in Combustion 

 may be exactly measured, with some Introductory Remarks upon the 

 Nature of different Coals,' by Andrew Ure, M.D. — In these researches, 

 which are still in progress, the first point (said Dr. Ure) which I seek to 

 ascertain is the proportion of volatile and fixed matter afforded by any 

 kind of fuel — as, for example, pit-coal — when a given weight of it is 

 subjected, in a retort or covered crucible, to a bright red heat. The result 

 of this experiment shows how far the coal is a flaming or gas coal, and 

 what quantity of coke it can produce. The second preliminary point of 

 importance which I determine with regard to coals, is the amount of 

 sulphur they may contain : a circumstance which has not hitherto been 

 made the subject of precise investigation, in this country at least, but 

 which is of great consequence, not only as to their domestic use, but to 

 their employment by the iron-master and the manufacturer of gas. That 

 good iron cannot be made with a sulphureous coal, however carefully 

 coked, has been proved in France by a very costly experience. In ge- 

 neral, when a coal leaves 15 or 16 per cent, of ferruginous ashes, we 

 may conclude with certainty that it contains sulphur in corresponding 

 proportion ; for this substance exists always, I believe, in pit-coal, in the 

 form of pyrites, but often disseminated or combined, so as to be invisible, 

 unless by microscopic means. The most ready and exact method of de- 

 termining rigidly the quantity of sulphur in any compound, is to mix a 

 given weight of it with a certain weight of carbonate of potassa, nitre, 

 and common salt, each chemically pure, and to ignite the mixture in a 

 platinum crucible. A whitish mass is obtained, in which all the sulphur 

 has been converted into sulphate of potassa. By ascertaining, with 

 nitrate of baryta, the amount of sulphuric acid present, that of sulphur 

 becomes known. By such a process, applied to different samples of 

 coals, sent to me for analysis, I obtained the following results : — 



