LIFE of Dr HUTTON. 49 



and condudled too ftricflly according to the rules of philofophical 

 analyfis. It proves that cuhn is the fmall, or refufe, of the infufi- 

 ble, or flone coal, fuch as that of Scotland for the moft part is ; 

 that the fmall of the fufible coal, by caking or uniting together, 

 becomes equally ferviceable with the large coal ; whereas the 

 fmall of the infufible, by running down like loofe fand, cannot 

 be made to burn in the ordinary way, and is ufeful but for 

 few purpofes, fo that it has been properly exempted from the 

 ufual duty on coal. A criterion is alfo pointed out for deter- 

 mining when fmall coal is to be regarded as culm, and when 

 it may be confidered as coal ; — if, when a handful of it is thrown 

 into a red-hot fhovel, the pieces burn without melting down or 

 running together, it decidedly belongs to the former *. 



In the conclufion, an exemption from duty was obtained for 

 the fmall coal of Scotland, when carried coaflwife, and this re- 

 gulation was owing in a great degree to the fatisfadlory infor- 

 mation contained in Dr Hutton's pamphlet. It was a ftep, 

 alfo, toward the entire abolition of thofe injudicious duties 

 which had been fo long levied on coal, when carried by fea be- 

 yond a certain diftance from its native place. This abolition 

 happened feveral years after the period we are fpeaking of, 

 much to the benefit of the country, and to the credit of the ad- 

 miniftration under which it took place. 



As Dr HuTTON always took a warm intereft in whatever con- 

 cerned the advancement of the arts, particularly in his native 

 country, he entered with great zeal into the projedl of an inter- 

 nal navigation between the Friths of Forth and Clyde. The 

 comparative merit of the different plans, according to which 

 that work was to be executed, gave rife to a good deal of difcuC- 

 fion, and even of controverfy. In thefe debates Dr Hutton 



G 2 took 



• A few copies of the Conjiderations on Culm are ftill to be found in the fliop of 

 C. Elliot, Edinburgh. 



