Both Rutherford and Priestley were anticipated by a Swedish chemist, Karl Wilhelm Scheele, one of a group of chemists who brought Sweden to the forefront of science in the eighteenth century.

One of these Swedes, George Brandt (1694-1768), had studied, about 1730, a bluish mineral that resembled copper ore but which, to the exasperation of the miners, yielded no copper when put through the usual treatment. The miners thought it was ore that had been bewitched by the earth-spirits they called "kobolds". Brandt was able to show that the mineral contained no copper, but contained, rather, a new metal (resembling iron in its chemical properties) which he named cobalt after the earth-spirits.

In 1751, Axel Fredric Cronstedt (1722-1765) discovered the very similar metal, nickel; Johann Gottlieb Gahn (1745-1818) isolated manganese in 1774, and Peter Jacob Hjelm (1746-1813) isolated molybdenum in 1782.

The discovery of these new elements by Swedes demonstrated the strides mineralogy was making in that nation. Cronstedt, for instance, introduced the blowpipe into the study of minerals. This was a long, narrowing tube which, when blown into at the wide end, produced a concentrated jet of air at the narrow end. This jet, directed into a flame, increased its heat.

When the heated flame impinged on minerals, information concerning the nature and composition of the mineral could be gathered from the color of the flame, the nature of the vapors formed, the oxides or metallic substances left behind, and so on. The blowpipe remained a key tool in chemical analysis for a century.

Enough knowledge was gained about minerals through new techniques such as that of the blowpipe, that Cronstedt felt justified in suggesting that minerals be classified not only according to their appearance but also according to their chemical structure. A book detailing this new form of classification was published in 1758.

This work was carried further by another Swedish mineralogist, Torbern Olof Bergman (1735-1784). Bergman evolved a theory to explain why one substance reacted with a second but not with a third. He supposed the existence of "affinities" (that is, attractions) between substances in varying degree. He prepared elaborate tables listing various affinities, and these tables were very influential during his lifetime and for a few decades afterward.

Scheele, who began life as an apothecary's apprentice, attracted the attention of Bergman, who befriended and sponsored him. Scheele discovered a variety of acids, including tartaric acid, citric acid, benzoic acid, malic acid, oxalic acid, and gallic acid in the plant kingdom; lactic acid and uric acid in the animal; and molybdic acid and arsenious acid in the mineral.

He prepared and investigated three highly poisonous gases; hydrogen fluoride, hydrogen sulfide, and hydrogen cyanide. (His early death is supposed to have been the result of slow poisoning by the chemicals he works with, which he would routinely taste.)

Scheele was involved in the discovery of most of the elements for which credit is given to his Swedish friends. Most important of all, he prepared oxygen and nitrogen in 1771 and 1772. He prepared oxygen by heating a number of substances that held it loosely, including the mercuric oxide used by Priestley, a couple of years afterward.

Scheele described his experiments carefully but, through the negligence of his publisher, the descriptions did not appear in print until 1777. By that time the work of Rutherford and Priestley had appeared, and they gained the credit for the discoveries.