In 1842 accordingly, when the slaves numbered 50,740 and the sugar crop filled 140,000 hogsheads, the plantations were but 668.[44] The raising of the tariff anew in that year increased the plantations to 762 in 1845 and they reached their maximum number of 1,536 in 1849, when more than half of their mills were driven by steam[45] and their slaves numbered probably somewhat more than a hundred thousand of all ages.[46] Thereafter the recovery of the cotton market from the severe depression of the early 'forties caused a strong advance in slave prices which again checked the sugar spread, while the introduction of vacuum pans and other improvements in apparatus[47] promoted further consolidations.
The number of estates accordingly diminished to 1,298 in 1859, on 987 of which the mills were steam driven, and on 52 of which the extraction and evaporation of the sugar was done by one sort or another of the newly invented devices.

The gross number of slaves in the sugar parishes was nearly doubled between 1830 and 1850, but in the final ante-bellum decade it advanced only at about the rate of natural increase.[48] The sugar output advanced to 200,000 hogsheads in 1844 and to 450,000 in 1853.

Bad seasons then reduced it to 74,000 in 1856; and the previous maximum was not equaled in the remaining ante-bellum years.[49] The liability of the crop to damage from drought and early frost, and to destruction from the outpouring of the Mississippi through crevasses in the levees, explains the fluctuations in the yield.

Outside of Louisiana the industry took no grip except on the Brazos River in Texas, where in 1858 thirty-seven plantations produced about six thousand hogsheads.[50] [Footnote 42: _DeBow's Review_, I, 55.] [Footnote 43: V.Debouchel, _Histoire de la Louisiane_ (New Orleans, 1851), pp.

151 ff.] [Footnote 44: E.J.Forstall, _Agricultural Productions of Louisiana_ (New Orleans, 1845).] [Footnote 45: P.A.Champonier, _Statement of the Sugar Crop Made in Louisiana_ (New Orleans, annual, 1848-1859).] [Footnote 46: DeBow, in the _Compendium of the Seventh Census_, p.