Woodfield looked at him from under his beetling brows, but went on stirring. "Matter is indestructible," he replied stolidly; and with this he tipped the contents of the mortar on to a sheet of paper and transferred them to a large fireclay crucible. "Now, Polton," said he, "is the furnace ready?"
Polton disengaged himself for a moment from the camera, and took up a position by the side of the big fireclay drum with his hand on the gas cock. Then Woodfield, having dropped three or four large iron nails into the crucible, carried the latter over to the furnace and lowered it into the central cavity. The cock was turned on by Polton and a match applied, whereupon a great purplish flame shot up with a roar from the mouth of the furnace; and even when this had been confined by the dropping on of the massive cover, the ironcased cylinder continued to emit a muffled, sullen growl.
While the crucible was heating, I transferred my attention to Thorndyke. The photographic operations were now concluded and the moulding wax had just been produced from a warmed incubator. Polton's curiosity—and mine—was about to be satisfied.
Thorndyke began by laying a thick slab of the warm and pliable wax on the middle of a smooth plate of varnished plaster, at each corner of which was a small, hemispherical pit, and dusting powdered French chalk sparingly over the level surface of the wax. Then he took the large fragment of bone, which bore the mysterious yellow stain, and laid it on the wax with the stained side uppermost, pressing it very gently until it gradually sank into the soft, pasty mass. Next, he took a somewhat smaller slab of wax and, having dusted its surface with French chalk, laid it on the fragment of bone, pressing it on gently but firmly, especially in the neighbourhood of the stain. Having squeezed some irregular-shaped lumps of wax on the back of the top slab, he fastened a strip of india-rubber round the edge of the plaster plate, so that it formed an upright rim, and turned to Polton. "Now mix a bowl of plaster—and mix it extra stiff, so that it will set quickly and hard."
With a soft brush he painted a thin coat of oil on the exposed portion of the plaster plate, up to the edges of the wax, and including the little circular hollows. By the time he had done this, Polton reappeared from the workshop with a basin of liquid plaster, which he was beating up with a spoon as if preparing a custard or batter pudding. As soon as the plaster began to thicken, he poured it on the wax and the oiled slab until it formed a level mass, nearly flush with the top of the india-rubber rim. In a surprisingly short time, the smooth, creamy liquid solidified into a substance having the appearance of icing-sugar, and when Polton had stripped away the india-rubber rim, exposing the edge of the new plaster slab, this part of the process was finished. "We will put this mould aside for the plaster to harden while we make the other mould," said Thorndyke.
"Aren't you going to make moulds of all the fragments?" asked Jervis.
"No," Thorndyke answered;" the photographs of the rest will be sufficient, and I don't think we shall want even those; in fact, what I am doing now is merely by way of extra precaution. We are obliged to destroy the fragments in order to make the analysis, so I am just putting their appearance on record. You never know what an ingenious defending counsel may spring on you."
As Polton produced a second plate of varnished plaster and Thorndyke began to prepare the wax for the next mould, I turned my attention once more to Professor Woodfield. He had now deserted the mortar—in which he had been preparing a further supply of "the stuff"—and taken up a position by the furnace, with a long pair of crucible-tongs in his hand. On the bench, hard by, was an iron plate, and on this an oblong block of iron in which were six conical hollows.
Presently Woodfield glanced at his watch, turned off the gas-cock, removed the cover of the furnace with his tongs, and, reaching down into the glowing interior, lifted out the nearly white-hot crucible. Instantly Marchmont, Humperdinck and Jervis gathered round to watch, and even Thorndyke left his mould to come and see the result of the first trial.
Having stood the crucible on the iron plate while he picked out the large nails, one by one, Woodfield lifted it and steadily poured its molten contents into the first hollow in the iron block, which they soon filled, and overflowing ran along the iron plate in glowing streams that soon grew dull from contact with the cold surface. I noticed that, as the crucible was slowly tilted, Thorndyke kept his eyes fixed on its interior, as also did Jervis and Woodfield; and, watching closely, I saw just as the vessel was nearly empty, what looked somewhat like a red-hot oil-globule floating in the last of the glowing liquid. This passed out as the crucible was tilted further, and disappeared into the iron mould; when Woodfield, having exchanged a quick, significant glance with Thorndyke, proceeded forthwith, in his matter-of-fact way to fill up the still red-hot vessel with another pound and a quarter of the late Septimus Maddock. "I suppose," said Marchmont," it is premature to ask you what is the final object of these very interesting operations?"
"It's no use asking me," replied Woodfield," because I don't know. I am searching for traces of a particular substance, but what may be the significance of its presence, I haven't the slightest idea. You'd better ask Dr. Thorndyke—and he won't tell you."
"No, I know," said Marchmont. "Thorndyke will never tell you anything until he can tell you everything. By the way, will the remains be completely destroyed or will it be possible to recover them?"
"They are not destroyed at all," replied Woodfield. "They are all in the slag that came out of the crucible. We shall simply put the slag in the urn. There is a little charcoal, soda and borax added, but nothing is taken away."
I could see that to the unchemical mind of Father Humperdinck, this was far from satisfactory, and I observed him poring, with obvious disapproval, over the dark-coloured, glassy masses of slag on the iron plate. "Ashes to Ashes" was an intelligible formula, but "ashes to slag" was quite another matter, for which no provision had been made in any known ritual.
After a rather hurried luncheon, the wax moulds were carefully opened and the fragments of bone picked out, when it was seen that each fragment had left a perfect impression on the wax surface into which it had been pressed. These hollow impressions were now filled with liquid plaster, and, when the latter had thickened sufficiently, the two halves of each mould were quickly fitted together and kept in close contact by a weight.
During the interval which was necessary to allow of the plaster setting quite firmly, I had leisure to note that Professor Woodfield had filled two more of the cavities in the iron mould. Now that the furnace was thoroughly hot, he was able to work rather more quickly, and he had economized time by leaving a crucible to heat while we were at lunch. He was preparing to take the fourth charge from the furnace when I observed Polton removing the weight from one of the moulds and hurriedly transferred my patronage to his part of the entertainment. The mould on which he was operating was the one bearing the impressions of the stained fragment of the innominate bone, and when he separated the two halves and exposed the newly-made cast inside one might have thought that the actual bone had been left in, so perfectly did the snowy plaster cast reproduce the dazzlingly-white calcined bone. But, naturally, the stain did not appear in the cast, a defect which Thorndyke proceeded at once to remedy by making a tracing of the exact position and extent of the coloured patch and transferring it to the cast. Then, and not till then, Thorndyke regretfully handed the original fragment to Professor Woodfield, who impassively dropped it into the mortar and pounded it into a mere characterless powder.
After the opening of the second mould and the removal of the casts, the interest of the investigation lapsed for a time. Woodfield's operations were, doubtless, the most important part of the procedure, but they were not thrilling to look on at. In fact they became by unvarying repetition, decidedly tedious, and when the last charge—containing