APPENDIX. (69) 



fperons circumftances of their early life, and for bearing her J='^;';;^°4, 

 equal fhare of tliofe anxieties and difappointments in bufinefs 

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



lives. 



Dr Roebuck's unremitt2d perfeverance in his chemical flu- 

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

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



The extenlive ufe of the vitriolic acid in chemiftry, and the 

 profpe(5l 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 m.aking 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 L emery the elder, and by 

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

 blifhed a profitable manufadlure 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 vefTels, 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 vefTels formerly ufed, lead ones of a great fize ; which 

 fubftitution, together with fundry other improvements in diffe- 

 rent parts of the procefs, completely effected his end. 



After the neceffary preparations had been made, MefTrs 

 Roebuck and Garbet eftablifhed a manufadlure of the oil of 

 vitriol at Preftonpans, in Scotland, in the year 1 749. This efta- 

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



feat 



