Preface, xv 



Terms are used in the following account of 

 the gypsum, without nice attention to their force; 

 as it is difficult more accurately to express our 

 present ideas. The plaister, is, for instance, called 

 a stimulant, a mariure. Some substances are said to 

 make a good footing for the plaister, that it wants 

 somciking to feed on, &c. When we know more 

 about it, we can establish a more appropriate and 

 correct phraseology. 



Several to whom I have applied for informa- 

 tion have not favoured me with it, from a disin- 

 clination, I presume, to throwing their thoughts 

 on paper. This discouraged me from extending 

 my correspondence. But I believe I have obtain- 

 ed the most material facts. Those who have an- 

 swered the queries, occupy land of every variety 

 of description, so as to comprehend the whole 

 range of the different soils on which the plaister 

 Is used. 



I shall be truly grateful, if any of those who 

 have been in the practice of applying the plaister, 

 will supply omissions, Jind rectify mistakes. 



I indulge a hope that men of chemical and 

 philosophical knowledge, will be induced farther 

 to examine and analyze this powerful substance, 

 with a view more accurately to discover its agri- 

 cultural properties, and the causes of its operation 

 on plants. The farmer, when taught by their dis- 



