210 On Lime and Mark. 



In presenting to the society this legacy of our late 

 worthy member, Mr. Lang, I cannot repress my sin- 

 cere regret for his loss. His constant desire to be use- 

 ful, was always evident ; and the efforts of a strong 

 natural understanding overcame the privation of litera- 

 ry acquirements. Such men are more valuable in so- 

 ciety, than are those who hide their talent under a 

 bushel ; or turn their faculties, however improved by 

 education, to subjects subservient to ambition, or self- 

 ish pursuits. 



I shall leave the subjects of his letter on their own 

 merits. I have always been of opinion, that English 

 writers knew little of the modus operandi of the gypsum; 

 and I have great reason to believe, that their acquaint- 

 ance with limey is not correct, or sufficiently extensive. 

 Mr. Lang and myself have taken much pains to pro- 

 cure, from our chemists, analises of our limestones ; 

 in hopes of confuting opinions, considered erroneous, 

 by facts. But we have heretofore been unsuccessful in 

 our endeavours. Until facts are settled, opinions must 

 remain as they are. Meantime, what Mr. Lang has 

 suggested will be a ground of inquiry ; and stimulate 

 some public spirited chemists to make investigations, 

 we know results ; and causes must continue problema- 

 tical. 



What he says of the effects of the offals of the whyn- 

 stone, or basalt, I have perceived in the application of 

 every kind of matter having sulphur in its composition. 

 There is a sharp dispute among the learned, concern- 

 ing the composition of basalt. Some affirm it to be a 

 volcanic production. Others that it consists of ochres, 



