The birth of chemistry / by G.F. Rodwell.

  • George Farrer Rodwell
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: The birth of chemistry / by G.F. Rodwell. Source: Wellcome Collection.

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    well known. Some affirmed that “ air is the food of fire,” some that “air nourishes fire.” The influence of a blast of air upon fire was well recognized ; we have seen that bellows were known at a very early date. When nitre—which for many centuries was one of the most important bodies in chemistry—came to be known, it was soon noticed that it produces intense ignition ; that, in fact, to direct a blast of air upon a red-hot coal, or to throw some nitre upon it, produced the same result, viz. greatly augmented combustion. Hence arose the idea that nitre and the air are in some way connected, for “things which are equal to the same are equal to each other.” This association of ideas may seem crude to us now, yet we must remember that nitre produces rapid com- bustion simply because it contains a great quantity of that constituent of the air, oxygen gas, which ordi- narily produces combustion. Thus the old natural philosophers, wandering in the dim twilight of expe- rimental knowledge, were not so far wrong in their supposition. The idea mentioned above was very prevalent two centuries ago: Robert Boyle speaks of the presence of a “ volatile nitre ” in the air ; Lord Bacon says that nitre contains a “volatile, crude, and windy spirit”; Clark attributed thunder and lightning to the presence of nitre in the air; Gassendi imagined that minute particles of nitre are diffused throughout the atmosphere. When we heat lead or tin in a current of air, these metals are respectively converted into a powder, or calx, and calcination was one of the most important processes in old chemistry. Calcina- tion seemed to be due more or less directly to the 1
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