The Zeeman Effect in the Spectrum of Argon

New measurements on the Zeeman effect of about 140 lines of the spectrum of argon have been completed, yielding $g$ values for several complete configurations, in particular the $3p^{5}6s$, $3p^{5}7s$, $3p^{5}4d$, and $3p^{5}5d$, and several levels of the $3p^{5}6d$. These have been compared with the $g$ values calculated by means of the quantum mechanics. In some cases the agreement is good, but $g$ sums show discrepancies. These are discussed in detail. The measurements differ in several cases from those of other observers. Concrete evidence of the $\mathrm{jj}$ parentage of some of the levels is presented.