# Boyle-Charles law

In gas laws, Boyle-Charles law refers to the combination of Boyle’s law (1969):

$PV = K\mid_{n,T} \,$

and Charles’ law (1787):

$V = KT\mid_{n,P} \,$

into a single gas law formula, of which several varieties seem to exist. A derivation still needs to be found as to the typical way in which these two equations are combined.

To cite one example, however, in one 1890 publication, the phrase “ideal perfect gas” was being used in relation to gases that obeyed the 'laws of Charles and Boyle' (or Boyle-Charles law), as defined by the following “characteristic equation”: [1]

$\frac{PV}{T} = K\,$

which says that the ratio of the product of the pressure and the volume of the gas by the temperature is constant for in ideal perfect gas. The term 'perfect' in this case a residual carry-over from the earlier days of attempts to make a 'perfect vacuum' (perfect gas) in gunpowder engine. In most cases the phrase Boyle-Charles law was a precursor synonym for the later term 'ideal gas law', which arrived after the concept of the mole or particle count unit n was invented. In short, the name Boyle-Charles law, in general sense, seems to be a layperson's term used as a synonym for the ideal gas law.

References
1. Robinson, William. (1890). Gas and Petroleum Engines: A Practical Treatise on the Internal Combustion Engine, (pg. 422). E. & F.N. Spon.