Two tracts on experiments conducted at Hudson's Bay on acids in relation to freezing mixtures by John McNab 1. Experiments on Mineral Acids and Rectified Spirits of Wine, for finding the greatest degree of cold In a preface by McNab he records that these experiments were made by direction from the Royal Society and carried on 'in a manner similar to those these of Mr Hutchins in 1782'. Tract annotated a received by the Royal Society as a gift from the author, 16 March 1786. 2. Experiments on the Congelation of Vitriolic and Nitrous Acids made at Fort Albany in Hudson's Bay Prefaced by a letter to Henry Cavendish, 4 September 1878. Tract annotated as received by the Royal Society as a gift from the author, 10 April 1788. 1784-1787