the late Mr. Henry. 227 
merchant, without, it may be hoped, diminish- 
ing his usefulness, or interfering with the 
prosperous management of his affairs. 
Besides the Lectures on the general prin- 
ciples of Chemistry, Mr. Henry delivered 
a course on the arts of Bleaching, Dyeing, 
and Calico-Printing ; and to render this course 
more extensively useful, the terms of access 
to it were made easy to the superior class of 
operative artisans. It was at this period, 
that the practical application was made in 
France of a philosophical discovery to one of 
the Arts which Mr. Henry was engaged in 
teaching, that shortened, by several weeks, 
the duration of its processes. In 1774, Scheele, 
a Swedish chemist, distinguished by the num- 
ber and great importance of his contribu- 
tions to chemical science, discovered, in the 
course of some experiments on manganese, 
the substance known successively by the 
names of dephlogisticated marine acid, oxy- 
muriatic acid, and chlorine. During several 
years afterwards, its properties were not ap- 
plied to any practical use, until its power of 
discharging vegetable colours suggested, to 
M. Berthollet of Paris, its employment in 
the art of bleaching. The first successful 
experiments with that view were made by 
M. Berthollet in the year 1786, and witha 
