The fundamental conception that underlay all Berthelot's chemical work was that all chemical phenomena depend on the action of physical forces which can be determined and measured.
Thomsen and Berthelot independently enunciated a generalization (commonly known as Berthelot's Third Principle, or Principle of Maximum Work), which may be stated in brief as follows: - Every pure chemical reaction is accompanied by evolution of heat.
To withstand the chemical action of the gases, the " calorimetric bomb " is lined either with platinum, as in Berthelot's apparatus, or with porcelain, as in Mahler's.
Berthelot's notation defines both initial and final systems by giving the chemical equation for the reaction considered, the thermal effect being appended, and the state of the various substances being affixed to their formulae after brackets.
Ostwald has proposed a modification of Berthelot's method which has many advantages, and is now commonly in use.
Are all of similar composition, and in Berthelot's opinion represent a collection of treatises made at Constantinople in the 8th or 9th century.
In Berthelot's opinion, the Syriac portions represent a compilation of receipts and processes undertaken in the Syrian school of medicine at Bagdad under the Abbasids in the 9th or 10th century, and to a large extent constituted by the earlier translations made by Sergius of Resaena in the 6th century.
Berthelot's works on the history of alchemy and especially his Chimie au moyen age (3 vols., Paris, 1893), the third volume of which contains a French translation of Jaber's works together with the Arabic text.