Thorndyke, who, in spite of his mental preoccupation, had been looking about him in his usual keen, attentive way, halted suddenly.
"Your reference to the _post-mortem_," said he, "reminds me that I forgot to put the ox-gall into my case."
"Ox-gall!" I exclaimed, endeavouring vainly to connect this substance with the technique of the pathologist. "What were you going to do with--"
But here I broke off, remembering my friend's dislike of any discussion of his methods before strangers.
"I suppose," he continued, "there would hardly be an artist's colourman in a place of this size?"
"I should think not," said Stopford. "But couldn't you got the stuff from a butcher? There's a shop just across the road."
"So there is," agreed Thorndyke, who had already observed the shop. "The gall ought, of course, to be prepared, but we can filter it ourselves--that is, if the butcher has any. We will try him, at any rate."
He crossed the road towards the shop, over which the name "Felton" appeared in gilt lettering, and, addressing himself to the proprietor, who stood at the door, introduced himself and explained his wants.
"Ox-gall?" said the butcher. "No, sir, I haven't any just now; but I am having a beast killed this afternoon, and I can let you have some then. In fact," he added, after a pause, "as the matter is of importance, I can have one killed at once if you wish it."
"That is very kind of you," said Thorndyke, "and it would greatly oblige me. Is the beast perfectly healthy?"
"They're in splendid condition, sir. I picked them out of the herd myself. But you shall see them--ay, and choose the one that you'd like killed."
"You are really very good," said Thorndyke warmly. "I will just run into the chemist's next door, and get a suitable bottle, and then I will avail myself of your exceedingly kind offer."
He hurried into the chemist's shop, from which he presently emerged, carrying a white paper parcel; and we then followed the butcher down a narrow lane by the side of his shop. It led to an enclosure containing a small pen, in which were confined three handsome steers, whose glossy, black coats contrasted in a very striking manner with their long, greyish-white, nearly straight horns.