An accompt of two books. I. Tracts, written by R. Boyle Esquire, containing new experiments touching the relation betwixt flame and air, and about explosions: An hydrostatical discourse, occasioned by some objections of Dr. Henry More, &c; To which is annex’t an hysrostatical letter, about a way of weighing water in water; of the air's spring on bodies under water; and about the differing pressure of heavy solids and fluids. In which accompt is occasionally inserted the publisher's reply to Mr. George Sinclair's paper, called a vindication of the preface of his Ars Nova & Magna Gravitatis & Levitatis. II. Experienze intorno à diverse cose naturali, fatte da Francesco Redi. In the first of the Tracts, which contains the <italic>New Experiments</italic> about the <italic>Relation betwixt Flame</italic> and <italic>Air</italic>, the Noble Author, after he had mentioned some of the chief difficulties, both in <italic>making</italic> and <italic>judging</italic> of these Experiments, and occurred also to some thoughts, that might arise in the Reader, about his not ascribing in these Narratives so absolute and equal a necessity of the <italic>Air</italic> to the production and conservation of all <italic>Flames</italic>, as divers Men have concluded from his former Experiments; after this, <italic>Isay</italic>, he divides this Discourse into three parts.