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Thomson's theory or combustion.

According to Dr. Thomson’s* theory, all the bodies concernedin combustion are either, 1 . Combustibles. ..2. Supporters of com-bustion...3. Incombustiblcs.

I. Combustible bodies are those substances which are saidin common language to burn. During the combustion they ap-pear to emit light and heat, and at the same time gradually wasteaway. When this change has reached its maximum, the processof combustion is at an end.

The class of combustibles is very numerous; but all thebodies belonging to it may be sub-divided into three sets,namely j 1. Simple combustibles,

2. Compound combustibles,

3. Combustible oxids.

Simple Combustibles.

1. SULPHUR, 3. DIAMOND,

2. PHOSPHORUS, 4. HIDROGEN GAS,

5. ALL THE METALS.

Compound Combustibles.

The compound combustibles consist of compounds, formed bythe simple combustibles uniting together two and two, and areof course much more numerous than the simple combustibles.They may be arranged under the five following heads :

1. SULPHURETS, 3. CARBURETS,

2. PHOSPHURETS, 4. ALLOYS,

5. SULPHURATED, PHOSPHORATED, AND CARBON-ATED HIDROGEN.

The combustible oxids are either simple, having a single base,or compound, having more than one base. All the simple com-bustible oxids, are by combustion converted into acids.

Nicholson’s Journal, 1802, No. V. p; 10.