I received your kind letters of the 16th and 20th instant. I thank you for your philosophical news. We have none here. I see your philosophers are in the way of finding out at last what fire is. I have long been of opinion that it exists every where in the state of a subtile fluid. That too much of that fluid in our flesh gives us the sensation we call heat; too little, cold. Its vibrations, light. That all solid or fluid substances which are inflammable have been composed of it; their dissolution in returning to their original fluid state, we call fire. This subtile fluid is attracted by plants and animals in their growth, and consolidated. Is attracted by other substances, thermometers, &c. &c., variously; has a particular affinity with water, and will quit many other bodies to attach itself to water, and go off with it in evaporation. Adieu. Yours most sincerely,