He was the earliest discoverer of oxygen and made an in-depth study of its properties. His research on oxygen began with 1767' s research on nitrite. At first, he heated saltpeter to obtain a property called "saltpeter volatiles", but the nature and composition of this substance are still unclear. Scheler repeatedly did the experiment of heating saltpeter, and found that when the saltpeter was heated to red in the crucible, it would emit dry and hot gas, and it would burn when it met with soot powder, giving off dazzling light. This phenomenon aroused Scheler's great interest
1773, he made relatively pure oxygen by various methods. Mainly includes:
(1) heating mercury oxide (HG0);
(2) heating nitrate (KNO 3);
(3) heating potassium permanganate (KMnO4);
(4) heating the mixture of silver carbonate (Ag2CO3) and mercury carbonate (HgCO3).
Scheler compiled these experimental results into a book called Fire and Air. The manuscript of this book was sent to the publishing house Swedrus at the end of 1775, but it was not published until 1777, and the manuscript was pressed in the publishing house for two years. Priestley, a British chemist, published a paper shortly after he discovered oxygen in 1774, which was in the early period of Buhler. Now it is thought in the history of chemistry that Scheler and priestley discovered oxygen independently. At that time, organic chemistry was still very naive. In the absence of theoretical knowledge, Scheler can find more than a dozen organic acids, such as:
① Inorganic acids: phosphoric acid (1774), arsenic acid (1775), molybdic acid (1778) and tungstic acid (1781);
② Other inorganic compounds: hydrogen fluoride (177 1), hydrogen arsenide (1775), copper arsenite (1778), hydrogen cyanide and cyanide (1782);
③ Organic acids: tartaric acid (1770), oxalic acid (1776), lactic acid and uric acid (1780), citric acid (1784), malic acid (1785), gallic acid and gallic acid.
④ Other organic compounds, such as casein and bone snail violet (1780), acetaldehyde and esters (1782) and glycerol (1783), are not easy.
In addition, Scheler has also done excellent research on the composition of air. If a lighted candle is covered with a glass cover, it will burn for a while and then go out. If all the air in the glass cover is pumped out, the candle will go out immediately. When the blacksmith strikes the iron, he blows into the bellows, and the fire will burn more brightly. Why do burning substances need air? Scheler became interested in burning. In order to find out this problem, Scheler used various chemicals and put them in a closed container, and conducted experiments again and again.
One day, Scheler put a piece of white phosphorus in an empty flask, covered it with a cork, and then heated it slightly from the outside of the bottle. White phosphorus burns immediately, giving off flames and white smoke. Soon, the fire went out, the fog dispersed and a layer of white material was deposited on the bottle wall.
After the flask cooled, Scheler immediately poured the flask into water and pulled out the cork. At this moment, something strange happened. When water fills 1/5 of the flask volume, the water level stops rising. He repeated the experiment several times and the result was still the same.
What's going on here? Where is the air of15? With this question, Scheler did another experiment.
He put some iron filings in a small bottle, poured some dilute sulfuric acid solution on it, then stuffed the bottle with a cork inserted in a glass tube and put it in a glass jar filled with water. The gas produced by the glass tube comes out of the water surface and is ignited by a flame covered with an empty burning bottle. The mouth of the flask is submerged under water, which can prevent outside air from entering the bottle. As hydrogen burns in a closed space, the water in the glass jar keeps pouring into the flask. When the flame is completely extinguished, the water entering the flask still accounts for only 1/5 of the flask volume.
Scheler is puzzled by this matter. Since 1/5 air was used in the combustion, why didn't the remaining 4/5 air disappear? Is the air left in the bottle different from the air lost in the burning?
So he did a series of experiments and put candles, charcoal and white phosphorus in the air left by burning. As a result, the candle went out immediately, the red-hot charcoal turned black quickly, and even the easily combustible phosphorus refused to catch fire. Put a few mice in and suffocate immediately.
Scheler finally realized that the air left by this kind of burning is really different from the "burned" air. Air seems to be made up of two completely different components. He thinks that one is "living air", which can help combustion, so it is called "flame air"; The other is "dead air", which has no effect on fire. Rats will suffocate and die, so they are called "useless air". Scheler is more interested in "flame air". After many experiments, Scheler quickly found a way to make pure "flame air". Scheler put some saltpeter in a glass retort and heated it on the stove. At the same time, he tied a deflated cow urine bubble around retort's neck. The saltpeter melts, and the released gas makes the cow urine bubble gradually expand. Then quickly remove the bovine urine bubble and store the gas in the bubble in the flask. Put red-hot charcoal, freshly blown firewood and phosphorus into these flasks respectively, and then the sparks around the charcoal burst and burn violently, giving off incandescent light; The wood with embers is burning again; Phosphorus generate gives off flame, which is dazzling. Scheler rushed out of the laboratory in high spirits, shaking a bottle in his hand and shouting "flame air!" " Flame air! And "flame air" is oxygen.