APPENDIX. (69) 



fperous circumftances of their early life, and for bearing her ^^^^'^^^ 

 equal fliare of thofe anxieties and difappointments in bufinefs 

 which {haded, but did not obfcure, the later period of their 



lives. 



Dr Roebuck's unremitted perfeverance in his chemical ftii- 

 dies, together with the fuccefs that attended them, led him, ftep 

 by ftep, to other refearches of great pubUc and private benefit. 



The extenfive ufe of the vitriolic acid in chemiftry, and the ^ 

 profpedl of its application to fome of the mechanic arts,, had 

 produced a great demand for that article, and turned the at- 

 tention of chemifts to various methods of obtaining it. The 

 late Dr Ward had obtained a patent for making it ; and, 

 though the fubftances from which it might be obtained, as well 

 as certain methods of obtaining it, had been known to others, 

 and particularly pointed out by Lemery the elder, and by 

 Glauber, yet Dr Ward was the firft, it is believed, who efta- 

 blifhed a profitable manufadure upon the difcovery. Much, 

 however, was wanting to render the acid of univerfal ufe in 

 chemiftry, and of extenfive utility in the arts, where great quan- 

 tities of it were required. The price of it was high, arifing 

 from the great expence of the glafs veflels, which were made 

 ufe of by Dr Ward in procuring it, and the frequent acci- 

 cidents to which they were liable in the procefs. 



Dr Roebuck had been, for fome time, engaged in making 

 experiments with a view to reduce the price, and at length dif- 

 covered a method of preparing it, by fubftituting, in place of 

 the glafs veffels formerly ufed, lead ones of a great fize ; which 

 fubftitution, together with fundry other improvements in diffe- 

 rent parts of the procefs, completely effe(5led his end. 



After the neceflTary preparations liad been made, Meffrs 

 Roebuck and Garbet eftabliftied a manufadture of the oil of 

 vitriol at Preftonpans, in Scotland, in the year 1749. This efta- 

 blifhment not a little alarmed Dr Ward, who attempted to de- 

 feat 



