he was never asked to compound the following prescription: Calcine vitriol until it becomes yellow, add mistletoe, hearts of peonies, elk's hoofs, and the pulverized skull of a malefactor; distill all these dry, rectify the distillate over castoreum and elephant's lice, then mix with salt of peony, spirit of wine, liquors of pearls and corals, oil of aniseed and oil of amber, and digest on a water-bath one month.'

Still at this time Chemistry stood only on Mount Abarim and gazed at the Promised Land which it was not to enter until the ensuing century.

To-day we know about eighty elements; he knew about fifteen.

In Scheele's day fire was procured by means of flint and steel with tinder-boxes and sulphur-tipped splints of wood. It was forty years after his death before the first friction matches were invented by the English druggist, John Walker, of Stockton-on-Tees.

Only after his body had turned to dust, was gas used for lighting, was the hydraulic press patented, was the Voltaic pile made, was electro-magnetism discovered, was the limelight of Drummond invented, and the Daguerreotype process introduced.

Scheele died in 1786, and it was not till the beginning of the nineteenth century that Dalton announced his atomic theory and formulated the law of definite proportions which became the immediate cause of innumerable discoveries. Mendeleyeff's important system, in which it is shown that the properties of the elements are periodic functions of their atomic weights, came much later still.

In 1805 Sertürner discovered the basic constituents of opium, and thus paved the way for the alkaloids, but Scheele never heard of morphine, strychnine or quinine.

By means of the galvanic battery, Humphry Davy did wondrous things he discovered element after element, he decomposed water into hydrogen and oxygen, he separated salts into acid and base, he resolved acids into their electro-positive and

electro-negative constituents, he simplified bases into the metal and oxygen,- but there was no voltaic chemistry while Scheele lived.

Michael Faraday began systematic work in the liquefaction of gases and liquefied chlorine, hydrogen sulphide, cyanogen, ammonia and sulphurous acid. On December 24, 1877, at a meeting of the French Academy a paper by Cailletet was read containing these welcome words: 'I have just this day liquefied oxygen and carbon monoxide.' There was another paper by Pictet announcing: To-day I liquefied oxygen at a pressure of 320 atmospheres and a temperature of — 140° C, obtained by means of liquid sulphurous and carbonic acid.' The patient Dewar succeeded in securing obstinate hydrogen not only in a liquid but even in a solid state. Mighty deeds; Scheele's heart would have leaped at them, but he never knew.

Nor did he ever know that urea, an organic body, could be produced artificially in a laboratory.

Scheele had not the hundredth part of the delicate and intricate instruments with which the chemist of to-day is supplied. His apparatus was of the crudest sort, and much of it he was compelled to manufacture himself. He never saw a polariscope, or a balance which weighed a pencil-mark. Had he seen a laboratory like Sir William Ramsay's, his actions would have resembled those of his great countryman, Linnæus the Botanist, when he first spied an English wild-flower, -the earth would have felt his knees.

When we remember these hardships and at the same time recall the immense amount of valuable work he accomplished, we realize what manner of man was Scheele. The pioneer who blazes the trail in an unknown forest, surely deserves as much credit as he who comes leisurely after and helps to widen the already-made path. If the second is the more cultured of the two, he is the less original.

Because of Scheele's devotion to it, mention must here be made of one of the most interesting hypotheses that ever en

tered into the history of chemistry- the Phlogistic theory. This doctrine which was introduced by Johann Joachim Becher and championed by George Ernst Stahl had special reference to the alterability of substances by fire. Its essential feature consisted in assuming that all matter which could burn was a compound, containing at least two constituents. On combustion, one of these remained behind and one escaped. The element which remained was named calyx, the principle which disappeared was called Phlogiston. It corresponded somewhat to the 'celestial heat' of earlier chemists. Since this Phlogiston existed in all combustible substances and always vanished on heating, it was believed that every time a substance was burned it grew lighter.

In due time it began to be pointed out that some substances when heated, instead of becoming lighter, become heavier, and that often the products of combustion weigh more than the substances burned. It was shown that when zinc is burned, it changes into a white powder which is heavier than the original metal.

Lavoisier knew that when phosphorus burns, the acid body formed by the combustion weighs more than the phosphorus did. But it takes a long time for a naked fact to destroy a theory intrenched in argument, and defended by dialectics. Yet already the casket of Phlogiston was being prepared, and Lavoisier was the immortal undertaker.

Oxygen was discovered by Priestley and Scheele, nitrogen was found by Rutherford, the air was analyzed by Cavendish, and a great light illumined the mind of the French chemist, and the death-knell of the doctrine of Becher and Stahl was rung. Hitherto, combustion was thought to be due to a chemical decomposition in which Phlogiston escapes, but Lavoisier now accounted for the phenomenon of combustion by chemical combination, oxygen or another element being taken up.

The cover was ready to be nailed to the coffin. And the talented wife of Antoine Laurent Lavoisier,- Liebig has told

us so,-robed as a priestess, committed to the flames on an altar, while a solemn requiem was chanted, the phlogistic system of chemistry.

After Copernicus there was no more excuse for astrology; after Darwin there was no more reason for immutability; and after Lavoisier there was no further justification for Phlogiston. But the roots of pre-conceived notions are long and strong, and take generations to uproot. Only one chemist of that age accepted the new truth. Sole among contemporary scientists, Joseph Black-forever illustrious as the discoverer of latent and specific heat-announced himself an adherent of the Lavoiserian doctrine of combustion.

Priestley, Cavendish and Scheele remained firm believers in the phlogistic theory which their researches had done so much to upset.

So Scheele was wrong, but what scientist has made no mistake? Galileo discovered a new heaven, but he laughed when Kepler claimed that the tide is influenced by the moon. Harvey discovered the circulation of the blood, but he saw no merit in Bartholin's researches on the lacteals and lymphatics. Perhaps we must say of these men as Carlyle said of Jesus, 'A great mon, a great mon, but he had his limitations.'

Science has a sorrowful list of wondrous youngsters who disappeared from life when the brain was still eager, and the spirit ardent. Scheele was one of these. In his forty-fourth year he was added to the roll of short-lived geniuses. Yet tho the days of his life were few, he labored long and lovingly, for he was in the service of science, and some of the benefits he rendered her are here recorded:

In 1769, while still in his twenties, he experimented with cream of tartar, from which compound he was the first to isolate tartaric acid. He sent a record of his experiments to Torben Bergmann, the foremost Swedish chemist. The professor was a generous friend, but at this time must have been absorbed in his own work, for he failed to convey the paper

to the Academy of Sciences at Stockholm, which, however, was later done by Anders Retzius.

As far back as 1669 the alchemist Brandt of Hamburg, while searching for the 'philosopher's stone' that converts lead to silver and ennobles brass to gold, distilled an evaporated mixture of urine and sand, and obtained, not the 'elixir of life,' but - phosphorus. This yellow waxy solid which shone so mysteriously in the dark, and burned with such a dazzling light, was exhibited in the courts of Europe and attracted the attention of lords and ladies who had never previously evinced a startling congenital predisposition for scientific pursuits. Phosphorus is used in medicine as a sexual aphrodisiac, and it would be interesting to know if it was the Merry Monarch and his royal revellers who discovered this therapeutic fact.

For a hundred years the peculiar phosphorescent element remained a chemical curiosity, costing about sixteen ducats an ounce. But in 1771 Scheele - building on Gahn's observation that phosphorus is a constituent of bone-ash — published a method still used in preparing the light-bringer. Bones are burned to remove all animal matter, and the remaining calcium phosphate is heated with hot sulphuric acid, producing phosphoric acid and calcium sulphate. The acid is then strained from the sulphate, concentrated, mixed with charcoal, and dried in an iron pot. Water escapes and metaphosphoric acid remains. The mixture is then transferred to a fireclay retort, strongly heated, and under the water appears the desired phosphorus.

Its principal modification is the red or amorphous phosphorus discovered by Professor Schrotter, of Vienna. Altho prepared from the yellow variety, its properties are essentially opposite. It is practically odorless, non-poisonous, non-phosphorescent, insoluble in carbon disulphide, non-decomposable in the air.

Both the yellow and the red phosphorus are employed in the manufacture of matches. Sweden is the world-leader in