TO THE RIGHT HONOURABLE THE EARL OF SHELBURNE, THIS TREATISE IS, WITH THE GREATEST GRATITUDE AND RESPECT, INSCRIBED, BY HIS LORDSHIP's MOST OBLIGED, AND OBEDIENT HUMBLE SERVANT, J. PRIESTLEY. THE PREFAC E. NE reason for the present publication has been the favourable reception of those of my Obfervations on different kinds of air, which were published in the Philofophical Transactions for the year 1772, and the demand for them by perfons who did not chufe, for the fake of those papers only, to purchase the whole volume in which they were contained. Another motive was the additions to my obfervations on this fubject, in confequence of which my papers grew too large. for fuch a publication as the Philofophical Tranfactions. Contrary, therefore, to my intention, expreffed Philofophical Transactions, vol. 64. p. 90. but with the approbation of the President, and of my friends in the fociety, a 3 |
