157 
and naphthaline , and on a new acid produced. 
baryta was then added, the whole evaporated to dryness, 
heated red-hot, washed with dilute muriatic acid to remove 
the baryta uncombined with sulphuric acid, and the sulphate 
collected, dried, and weighed. The results were inconstant ; 
but the sulphate of baryta obtained, always much surpassed 
that furnished by the former method. Judging from this 
circumstance that the sulphuric acid in the salt was more 
than an equivalent for the baryta present, many processes 
were devised for the determination of its quantity, but were 
rejected in consequence of difficulties and imperfections, aris- 
ing, principally, from the presence and action of so much 
carbonaceous matter. The following was ultimately adopted. 
A quantity of per-oxide of copper was prepared by heating 
copper plates in air and scaling them. A sufficient quantity 
of pure muriatic and nitric acids were provided, and also a 
specimen of pure native carbonate of baryta. Seven grains 
of the salt to be examined were then mixed with seven grains 
of the pulverized carbonate of baryta, and afterwards with 
312 grains of the oxide of copper. The mixture being put 
into a glass tube was successively heated throughout its 
mass, the gas liberated being passed through a mixture of 
baryta water and solution of muriate of baryta. It was found 
that no sulphurous or sulphuric acids came off, or indeed 
sulphur in any state. The contents of the tube were then 
dissolved in an excess of nitric and muriatic acids, above that 
required to take up all that was soluble ; and a little solution 
of muriate of baryta was added for the sake of greater 
certainty. A portion of sulphate of baryta remained undis- 
solved, equivalent to the sulphuric acid of the salt experi- 
mented upon, with that contained accidentally in the oxide of 
