Halle, 1697 [from Henry Marshall Leicester and Herbert S. Klickstein, A Source Book in Chemistry 1400-1900 (New York: McGraw Hill, 1952)]
The same thing works very well with sulfur, when certainly two parts, or better, three parts of alkali salt and one of pulverized sulfur are successively poured into and fused in a crucible. There is formed liver of sulfur. This, in the space of a quarter of an hour more or less, by fire alone, without any addition, can be converted to such a salt as is obtained from oil of sulfur per campanum and salt of tartar, that which is commonly called vitriolated tartar. There is no more trace of sulfur or alkali salt, and in place of the red color of the liver, this salt is most white; in place of the very evil taste of the liver, this salt is very bitter; in place of the easy solution, nay, the spontaneous deliquescence of the liver, by reason of its alkali salt, this salt is the most difficult of all salts except tartar of wine to be dissolved; in place of the impossibility of crystallizing the liver, this is very prone to form almost octahedral crystals; in place of the fusibility of the liver, this is devoid of all fusion.
If this new salt, from the acid of sulfur and alkaline salt formed as stated above when the phlogiston has been used up, is treated with charcoal, in the space of a quarter of an hour the original liver of sulfur reappears, and this can be so converted a hundred times. ...
I can indeed show by various other experiments how phlogiston from fatty substances and charcoal enters very promptly into metals themselves and regenerates them from the burned calx into their own fusible, malleable, and amalgamable state.
Halle, 1718 [from Henry Marshall Leicester and Herbert S. Klickstein, A Source Book in Chemistry 1400-1900 (New York: McGraw Hill, 1952)]
Now the first thing to consider concerning the principle of sulfur is its properties, as follows:
According to these conditions and intentions, I now have demonstrable grounds to say, first,
Toward fire, this sulfur principle behaves in such a manner that it is not only suitable for the movement of fire but is also one and the same being, yes, even created and designed for it.
But also, according to a reasonable manner of speaking, it is the corporeal fire, the essential fire material, the true basis of fire movement in all inflammable compounds.
However, except in compounds, no fire at all occurs, but it dissipates and volatilizes in invisible particles, or at least, develops and forms a finely divided and invisible fire, namely, heat.
On the other hand, it is very important to note that this fire material, of and by itself and apart from other things, especially air and water, is not found united and active, either as a liquid or in an attenuated state. But if once by the movement of fire, with the addition of free air, it is attenuated and volatilized, then by this in all such conditions it is lost through unrecognizable subtlety and immeasurable attenuation, so that from this point on no science known to man, no human art, can collect it together or bring it into narrow limits, especially if this occurred rapidly and in quantity.
But how enormously attenuated and subtle material becomes through the movement of fire is shown by experience, which furnishes a field for thought and which also delights us.
From all these various conditions, therefore, I have believed that it should be given a name, as the first, unique, basic, inflammable principle. But since it cannot, until this hour, be found by itself, outside of all compounds and unions with other materials, and so there are no grounds or basis for giving a descriptive name based on properties, I have felt that it is most fitting to name it from its general action, which it customarily shows in all its compounds. And therefore I have chosen the Greek name phlogiston, in German, Brennlich. ...
The seventh and last consideration was where it could be found or occurred. The answer to this is now also in part easy to give from the discussion already presented, and from consideration that all corporeal compounded things have more or less of this substance, in all the so-called "kingdoms": vegetable, animal, and mineral. As then in the first two kingdoms there is contained a great amount of this principle, and all their parts are intimately penetrated and combined with it (except the watery parts which occur in them, but which still are not entirely free from it as long as they are in the body), then it is chiefly found in the fatty materials of both kingdoms.
In the mineral kingdom there is nothing but water, common salt, pure vitriolic salts, and light sand and stones in which the substance is little or not at all found. On the other hand, coal and bitumen are full of it; sulfur, not indeed in weight, but in the number of its finest particles, is completely possessed with it. Not less is it found in all inflammable, incomplete, and so-called "unripe" metals.
Norimbergae, 1723 [translated by Peter Shaw (1730), from Henry Marshall Leicester and Herbert S. Klickstein, A Source Book in Chemistry 1400-1900 (New York: McGraw Hill, 1952)]