the Coal-measures in co. Tyrone. 



215 



were made of different portions of these specimens; and as a 

 considerable variability appeared to exist in their composition, so 

 as to show the extremes of this variation, the results of three 

 analyses of three different pieces of each have been given, these 

 having been selected from a number of others closely resembling 

 them. 



The analyses were made in the usual way, in a current of oxy- 

 gen gas, the apparatus being swept at the end of the operation 

 by a current of air. To avoid any loss from the potash-bulbs, 

 the precaution was taken to attach two U tubes, one containing 

 marble and caustic potash, and the other pumice moistened with 

 sulphuric acid. The combustion-tube was more than half filled 

 with copper oxide ; and in the remaining part was placed the pla- 

 tinum boat and a long copper boat containing copper oxide, the 

 platinum boat lying between the copper boat and the column of 

 copper oxide. It was found most convenient to use a platinum 

 boat at least 80 millims. long, as the combustion of the coal was 

 thereby greatly facilitated. Not more than '15 to *3 grm. was 

 employed for an analysis ; and this was taken from a large quan- 

 tity that had been powdered and well mixed. Before calculating 

 the carbonic anhydride and water from the increase in weight of 

 the potash-bulbs &c, certain corrections were applied. The 

 amounts of these corrections had been previously ascertained by 

 a number of blank experiments, in which known quantities of 

 air and oxygen had been passed through the apparatus, and the 

 weight of carbonic anhydride and water present determined. 

 Though the air and oxygen were first purified by being sent 

 through large U tubes containing caustic potash and sulphuric 

 acid, there was always an increase in weight in the calcium- 

 chloride-tube and the potash-bulbs ; it is therefore necessary to 

 apply this correction in accurate experiments. 



(a) Lignite from Ballintoy, 

 co. Antrim. 



1 

 (|8) Coal from 5-foot 



Main, Drumglass 

 Colliery, co. Tyrone. 



(y) Cannel-coal 



from Coalisland, 



co. Tyrone. 





(1) 



(2) 



(3) 



(1) 



(2) 



(3) 



(1) 



(2) 



(3) 



Carbon 



Hydrogen ... 



Oxygen and 

 nitrogen... 



Sulphur 



Ash..... 



473 



6-31 



31-49 



149 



47-8 

 6-25 



30-85 

 151 



48-1 

 5-96 



3064 

 15-3 



73-31 

 7-02 



13-77 

 1-6 

 4-3 



76-5 

 6-42 



12-93 

 1-45 



2-7 



78-9 

 630 



10-35 

 1-5 



2-95 



73-38 

 6-01 



3-44 

 23 



14-87 



77-58 

 5-53 



2-77 



2-11 



12-01 



79-07 

 5-12 



201 

 1-91 



11-89 





