An example of an historical scientific notion that would today be considered an alternative conception:
"WE may now proceed to consider sulphureous substances, with regard to their solubility in water, and to the part which these bodies have acted in consolidating the strata of the globe.
THE sulphureous substances here meant to be considered, are substances not soluble in water, so far as we know, but fusible by heat, and inflammable by means of heat and vital air. These substances are of two kinds; the one more simple, the other more compound.
THE most simple kind is composed of two different substances, viz. phlogiston, with acid or metallic substances; from which result, on the one hand, sulphur, and, on the other, metals, both properly so called. The more compound sort, again, is oily matter, produced by vegetables, and forming bituminous bodies.
THE first of these is found naturally combined with almost all metallic substances, which are then said to be mineralized with sulphur. Now, it is well known, that this mineralizing operation is performed by means of heat or fusion; and there is no person skilled in chemistry that will pretend to say, this may be done by aqueous solution. The combination of iron and sulphur, for example, may easily be performed by fusion; but, by aqueous solution, this particular combination is again resolved, and forms an acido-metallic, that is, a vitriolic substance, after the phlogiston (which refuses aqueous solution) has been separated from the composition, by means of the joint operation of vital air.
James Hutton (1788) Theory of the Earth
