Early in the winter of 1787, as soon as the cold was sufficiently intense, he began to repeat the experiments of Dr. Fordyce (‘Transactions of the Royal Society,’ vol. lxxv.) on the weight said to be acquired by water in the act of freezing; and, being possessed of a most excellent balance belonging to the Duke of Bavaria, he soon came to the conclusion that all attempts to discover any effect of heat upon the apparent weights of bodies would be fruitless. He had previously, in April 1785, convinced himself of the errors that arose from currents of air and from the drying of the cords by which the scales were hung. These experiments were made into a paper entitled ‘An Inquiry concerning the Weight Ascribed to Heat.’ This was read before the Royal Society, May 2, 1799. In May and June 1786 he made experiments on the production of air from water exposed to light. These were read before the Royal Society, February 15, 1787. When engaged in his experiments on the conducting powers of various bodies with respect to heat, and particularly of such substances as are used for clothing, he made experiments on the relation between their conducting power and their power of absorbing moisture, but found none. Flannel and fur, contrary to his expectation, absorbed much more moisture from the air than silk and cotton. On this he forms an idea of the good of wearing flannel. This, the weakest of his papers, was read to the Royal Society, March 22, 1787. In the spring of 1791 a large building was erected in the neighbourhood of Munich, on the ground destined for the exercise of the artillery, where a most complete apparatus was put up for measuring the velocities of cannon bullets by the recoil of the gun, and also by the pendulum at the same time, and with this apparatus a great number of interesting experiments were made. He observed that the force of the charge was always sensibly increased when the gun was discharged by firing a pistol (constructed for that use) into the vent, instead of using a priming and a common match for firing off the gun. These experiments were continued in 1792, and in 1793 they were shown to Dr. Blagden, who was in Munich during the absence of Sir B. Thompson in Italy for his health. The principal objects in view were to determine the expansive force of the elastic vapour generated in the combustion of gunpowder in its various states of condensation, and to ascertain the ratio of its elasticity to its density, and to measure the utmost force of this fluid in its most dense state.