Sulphuric acid specific heat

If myrcene be heated with glacial acetic acid to 40° for three to four hours, with the addition of a little sulphuric acid, hydration takes place, and an alcohol, which is termed myrcenol is formed. This body is an oil, of specific gravity 0 9032, refractive index 1 4806 at 15°, and boiling-point 99° at 10 mm. pressure. It yields a phenylurethane melting at 68°. 

Specifically for the synthetic organic compounds, the Pharmacopoeia prescribes values for sulphated ash. The sulphated ash is determined by a double ignition with concentrated sulphuric acid. Metals thus remain as sulphides that are usually stable to heat. The method is one of some precision, and provides results which are rather more reproducible than those obtained by simple ignition. 

Another universal method of development consists of heating the plate after spraying it with sulphuric acid, which carbonises the compounds to make them visible. This approach, however, cannot be used in quantitative TLC. It is preferable to develop the plate by using a general (phosphomolybdic acid) or specific (ninhydin in alcohol for amino acids) reagent. Hundreds of reagents have been described that can introduce chromophores or fluorophores into the analyte molecules after separation. 

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