[11] This necessary attention to economy also aided the simplicity of his apparatus, and was the means in some degree of improving it in this important respect. This plainness of his apparatus rendered his experiments easy to be repeated, and gave them accuracy. In this respect he was like his great Cotemporary Scheele, whose discoveries were made by means easy to be procured and at small expence. The French Chemists have adopted a practice quite the reverse. T. C. My first publication on the subject of air was in 1772. It was a small pamphlet, on the method of impregnating water with fixed air; which being immediately translated into French, excited a great degree of attention to the subject, and this was much increased by the publication of my first paper of experiments in a large article of the Philosophical Transactions the year following, for which I received the gold medal of the society. My method of impregnating water with fixed air was considered at a meeting of the College of Physicians, before whom I made the experiments, and by them it was recommended to the Lords of the Admiral (by whom they had been summoned for the purpose) as likely to be of use in the sea scurvy. The only person in Leeds who gave much attention to my experiments was Mr. Hay, a surgeon. He was a zealous methodist, and wrote answers to some of my theological tracts; but we always conversed with the greatest freedom on philosophical subjects, without mentioning any thing relating to theology. When I left Leeds, he begged of me the earthen trough in which I had made all my experiments on air while I was there. It was such an one as is there commonly used for washing linnen. Having succeeded so well in the History of Electricity, I was induced to undertake the history of all the brandies of experimental philosophy; and at Leeds I gave out proposals for that purpose, and published the _History of discoveries relating to vision light and colours_. This work, also, I believe I executed to general satisfaction, and being an undertaking of great expence, I was under the necessity of publishing it by subscription. The sale, however, was not such as to encourage me to proceed with a work of so much labour and expence; so that after purchasing a great number of books, to enable me to finish my undertaking, I was obliged to abandon it, and to apply wholly to original experiments.[12] [12] Many of the subscriptions remained unpaid.