LITERARY AND SCIENTIFIC. 59 



remarked, the workmanship, or the fabric, is destroyed, but the materials are 

 neither lost, nor made away with. The latter instance, in particular, was 

 noticed as being merely a change from the solid to the aeriform state. 

 "It is the business of Chemistry,'* said Mr. A., "to investigate iheKe and 

 similar changes, and to inquire into all the circumstances which can influence 

 them." 



Many interesting observations were here made upon the imponderable agents 

 Heat, Light, and Electricity, and Mr. Addison shewed that all simple elements 

 might be arranged into two classes — the eleciro-positive And the electro-negative i 

 from the former Mr. A. selected hydrogen, nitrogen, sulphur, phosphorus, and 

 carbon, and from the latter oxygen — detailing the several properties peculiar to 

 each, and giving a succinct account of the various compounds which they form 

 by combination with each other. Water was shewn to be a compound of two 

 invisible gases, oxygen and hydrogen ; and a very beautiful experiment was 

 exhibited, in which a small mass of platina by being merely suspended in a 

 current of hydrogen gas, was rendered red-hot, remaining so as long as the 

 stream of invisible matter impinged upon it. Mr, Addison explained that this 

 effect was produced by the union of the hydrogen with the oxygen of the atmos- 

 phere, effected by the platina which was rendered red-hot thereby, the result 

 being pure water, which was copiously deposited in pearly drops of dew upon a 

 small glass receiver which Mr. Addison held for a short time over the glowing 

 platina. 



Sulphuric acid (oil of vitriol) is a compound of sulphur and oxygen. Nitric 

 acid (aquafortis) of nitrogen and oxygen. Ammonia (hartshorn j of hydrogen 

 and nitrogen ; the two last are colourless fluids, and formed by the union of 

 two invisible gases, yet totally dissimilar in all their qualities. The combus- 

 tion of sulphur in oxygen gas was shewn, and the beautiful blue or purple light 

 emitted called forth the admiration of the audience. 



** There is nothing which excites the wonder of the chemical student more 

 than the tremendous powers which the particles of matter in certain modes of 

 combination display ; instances of it are afforded in the vapour and in the freez- 

 ing of water ; to the power evinced by the former the steam-engine owes all its 

 usefulness ; and the bursting of strong leaden pipes during severe frosts are 

 familiar demonstrations of it in the latter. The vast power derived from the 

 combustion of gimpowder is another sufficiently homely example. " There is a 

 compound of silver," said Mr. Addison, " which can hardly be handled without 

 exploding ; and another of mercury which explodes violently by a slight blow. 

 The chloride of nitrogen is another hazardous compound, it is an oil-like fluid, 

 decomposed by many combustibles, with powerful detonation : Dulong, who 

 discovered it, lost an eye and the use of a finger before he was aware of its 

 dangerous nature ; and Sir H. Davy was wounded in the face by the effects 

 arising from its sudden decomposition." 



The various combinations of phosphorus and carbon were then briefly 

 noticed, and the atomic theory, with the laws of definite combination and pro- 

 portionate numbers popularly explained. This was followed by illustrations of 

 the nature of combustion ; and the brilliancy of flame was shewn to depend 

 upon the large proportions of carbon carried up and burnt in the hydrogen 

 which forms the body and figure of the flame, for instance, of a candle. 



This interesting and instructive lecture was concluded by a brief history of the 

 various theories which have at one period or another prevailed upon the subject 

 of combustion — theories which have now all given way before the experimen- 

 tally established doctrines of modern chemistry, beautifully developed by the 

 researches of Hooke, Mayow, Cavendish, Lavoisier, &c: — and combustion is 

 proved to consist in the union of the elements composing the combustible with 

 the ponderable part of the oxygen of the air, the results, in all ordinary cases, 

 being water and carbonic acid, which are dissipated in the atmosphere. 



We cannot conclude this brief notice of Mr. Addison's lecture without giving 

 our readers the following pertinent observations with which it closed : — 



" Whatever may have been the rapid strides of chemical discovery within the 

 last century, more, much more, remains for future investigation. The farther 

 we advance in any branch of the study of Natural Philosophy, the more its 

 circle instead of closing on us, widens j when we reach some distant but seem- 



