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noticed: much information may be derivedfrom Monsieur Du Hamel, and much morefrom the well-directed experiments of Mr. Til-let*. Immense strides have been made in thiscareer, by the illustrious Bergman; Dr. Priest-ley’s experiments have thrown a new light on this,as well as on every other object of natural phi-losophy. Mr. Lavoisier ’s new theory explainsmany circumstances, before inexplicable; dis-coveries of great importance have been madeby Mr. Senebier and Dr. Ingenhouz: even Mr.Young has not always confined his attention totire mere practical part, but sometimes happilyextended it to objects of a more general andspeculative nature; but the fullest light, per-haps, has been thrown on this subject by thelate discoveries of Mr. Hassenfrazf.

If the exact connexion of effects,' with theircauses, has not been so fully and so extensivelytraced in this as in other subjects, we must at-tribute it to the peculiar difficulties of the in-vestigation. In other subjects, exposed to thejoint operation of many causes, the effect of

* Mem. Par. 1772. t Annates Chymiques, Vol. 13,14.B 2