[ 456 ] 
the latl difference of whofe numerators become equal to nothing, p* 401 — 407. Part 
III. containing obfervations on a correilion which is neceffary in inveftigating the Aims 
<of certain fcries by collecting two terms into one, with its application to a variety of 
cafes, p. 407 — 416. 
Inflammable air. See Phlogifion. The origin and nature of explained, p. 196 — 197. 
Is that very principle which alone is truly inflammable, as has been (hewn by Mr. 
Volta, p. 197. Is alfo the principle which reduces metallic earths to a metallic Hate, 
-and gives them their metallic fplendour, p, 199. Is the i'ubltance which, with vitriolic 
acid, forms fulphur, p. 200. Acids cannot be the bafis of inflammable air, and 
why, p. 202. Neither can earths or refpirable air, p. 203. Different experiments 
on inflammable air, with obfervations, p. ao^etfeq. The.reafon why inflammble 
air mixes fo eafily with water, and phlogilton, fuppoied to be the fame fubflance, 
conlfantly repels, and is repelled by ir, p. 209. Effedts produced by Dr. Prieftley, by 
melting the calces of iron, copper, lead, and tin, in inflammable air by means of a 
burning glafs, p. 210. See FAcRricity. 
Ingcn-hsufZy I)r. John. S^e Vegetable Kingdom. 
Inhabitants. Two methods of calculating the number of, in any place, where a nume- 
rical furvey cannot be obtained, p. 39. Remarkable coincidence between thofe two 
meafures, p. 40. 
Iron works. An account of fome fcoria from, which refemble the vitrified filaments 
deferibed by Sir William Hamilton, p. 30. Filaments from Mount Vefuvius and the 
volcano in the Ifle of Eourbon, deferibed, ibid. See Slag, Smelting Houfes . Sir 
William’s opinion concerning the formation of thofe filaments, p. $t. 
K. 
King-crab. See Monocu/us Polyphemus. 
Kir wan, Richard. See Saline Subjlances , Sulphur w 
Kraft , Mr. See Thermometer. 
L. 
Lamp-micrometer. Defcription of, and the method of ufing it, by Mr. William Her- 
fchel, p.163. The natural imperfections of the parallel wire-micrometer, ibid. The 
lamp-micrometer, which is free from all thofe imperfections, and has the advantage 
of a very enlarged fcale, deferibed, p. 165. Its ufe, p. 167. Capable of great 
improvement by the application of wheels, pinions, See. p. 168. The application 
of this inflrument explained, p. 169. And exemplified, p. 170. The meafures of 
this micrometer not confined to double ftars only, but may be applied to any other 
objedts that require the utmoft accuracy, p. 117. 
Leibnitz , 
