should rather say it was. The discoverywill create the greatest interest in the scientific world. Other gaseshave all been handled as true liquids in measurable quantities, whileuntil now hydrogen has only been seen in clouds or droplets, and nevercollected into a liquid mass. Upstairs, however, there is actually aglass bowl of liquid hydrogen. The experimenter, whoever he is, hasdetermined at last the exact temperature at which it will liquefy, andthus a field for quite new researches, as also for new generalisations,has been thrown wide open."
"But why is the discovery so very important?" I asked, still puzzled atthe doctor's unusual enthusiasm.
"Briefly, because by it physicists and chemists can henceforward obtaintemperatures lying within thirty-five degrees from the so-calledabsolute zero of temperature--minus 459 degrees Fahrenheit. Apossibility is thus given to study physical bodies in the vicinity ofthat point, which represents, so to say, the death of matter--that is,absence of the molecular vibrations which we describe as heat."
This explanation, technical though it was, interested me. I knew DoctorLees Knowles to be a rising man, and when reporting lectures at theRoyal Institution had often noticed him among the audiences. There wasno doubt that he was highly excited over the discovery, for, likemyself, he had seen the liquid hydrogen boiling without any visibleheat. In the papers there had been lots about Professor Dewar'sexperiments in the liquefaction of oxygen, fluorine and thenewly-discovered helium, and I remembered how all his efforts to bringhydrogen to a liquid state had failed. Now, however, the mysteriousoccupier of that house had succeeded, and every known gas could now beliquefied.
"But the murder," observed Patterson, his thoughts reverting to thecrime, for to him the most wonderful scientific discovery was as naught."Can you form absolutely no opinion as to how it was accomplished?"
The doctor shook his head.
"There is nothing whatever to account for their sudden death, as far asI can observe," he answered. "To the woman, however, death must havecome instantly, while the man must have fallen and expired a few secondslater. There seem many mysterious features in the affair."
"The discoverer of this latest scientific fact is undoubtedly the oldman who is absent, the father of the dead girl. From him we may learnsomething to lead us to form conclusions," I suggested.
"An old man!" echoed Dr. Knowles. "Tell me about him."
Briefly Patterson related all that had been told us by the neighbours,and when he had finished the doctor exclaimed--
"Then I can tell you one thing which is proved undoubtedly. The old manseen to go in and out was in reality a young one, for while looking overthe laboratory I came across a white wig and a make-up box, such as isused by actors. Go upstairs and you'll find a complete disguise there--broadcloth coat, pepper-and-salt trousers baggy at the knees,old-fashioned white vest, and collars of antique pattern."
"Surely that can't be true!" Patterson exclaimed in amazement.
"It certainly is," the doctor asserted. "Depend upon it that the manlying upstairs dead was the man who has been making these successfulexperiments, and who for some unknown reason desired to conceal hisidentity. Recollect that they had few friends, if any, and that theirman-servant was a most discreet foreigner, who never gossiped."
"Then you think that to the world they assumed the position of fatherand daughter, while in reality they were husband and wife?" I said.
"Most likely," responded the doctor. "A man to make experiments on anelaborate scale as he has must necessarily have been absorbed in them.Indeed, that apparatus must have taken a year to prepare, and no doubthe has been making constant trials for months. He probably intended togive forth his discovery to the world as a great surprise, but has beenprevented from doing so by some extraordinary combination ofcircumstances which has resulted in his death."
At that instant we heard a voice in the hall--a quick, sharp voiceextremely familiar to me, but nevertheless it caused me to start. Nextinstant, however, there entered the room the well-known figure of DickCleugh.
"Hulloa, old fellow!" he exclaimed, greeting me and taking me aside. "Ithought I'd run down and see what's in this. Funny affair it seems,doesn't it?"
"Yes," I answered. "A most remarkable mystery. But why have you comeout here?"
"Soon after you left I went to find Lily, but she's gone into thecountry. So having nothing else to do I came down to see what hadoccurred. I knew, of course, from Patterson's telegram, that it wassomething unusual."
"Have you been upstairs?"
"Yes, I've been worrying around this last half-hour, while you andPatterson have been making inquiries next door. I've been having a lookabout with the Doctor. It seems that there's some wonderful apparatusin the laboratory--a discovery for liquefying hydrogen. Has he told youabout it?"
"Yes," I responded. "What's your theory?"
"By Jove! old fellow," he said smiling, "the whole affair is so devilishuncanny, with those snakes upstairs, water boiling without any heatbeneath it, and one thing and another, that I'm utterly at a loss how toaccount for it all."
"You think they've been murdered?"
"Of course," answered the astute Cleugh. "But the doctor can't discoverhow. There is not a scratch upon them. The discovery of those flashnotes on the man looks as though he were a bit of a swell swindler,doesn't it?"
"Yes," I said. Then taking him across to the dining-table I explainedhow we had discovered the three cards concealed beneath the plates.
He took the cards in his hand, turning them over, and examining themcarefully.
"Strange," he ejaculated. "This adds still another phase to the affair.It is really a most sensational discovery, and will work up well forto-morrow."
"No, Mr. Cleugh," put in Patterson quickly, overhearing his remark, "Ibeg of you to publish nothing whatever about it until I give youpermission. In this we are bound to preserve secrecy for the present inorder that our inquiries may not be thwarted. Even the neighbours willremain in ignorance of the real nature of things, so carefully do Iintend to guard against any public sensation. Whatever information Ican give you I will do so willingly, in order that you can prepare youraccount of it, but remember that not a word must be published until Igive you permission."
"Quite right," observed the doctor. "In such a matter as this anysensation in the Press might frustrate all your efforts to arrive at thetruth."
"Very well," answered Dick, a trifle disappointedly. "Of course you'llgive nothing to anybody else. I want to be first in the field with it."
"Of that I give you my word. Not a soul will know of this discoveryoutside the persons in this house at the present moment. Come, let's goupstairs and speak to Boyd," and while the doctor wished us good eveningand left, my two friends accompanied me upstairs, where in thedrawing-room the detectives were continuing their searchinginvestigation.
"The woman is decidedly good-looking, isn't she?" observed Cleugh as weentered.
Instinctively I turned towards the chair in which the body was stillreclining, but next instant, with a loud cry of dismay, which at thesame moment was echoed by Patterson, I stood aghast, rigid, immovable.
The sight which met our eyes was utterly bewildering.
The woman we had discovered there, so lovely in form and feature, had awealth of auburn hair, and eyes of a deep intense blue, while, amazingthough it was, this woman before us was quite ten years older,dark-complexioned, with hair which in that light seemed blue-black, andhalf-closed eyes as dark as jet.
"Good Heavens!" I gasped. "Look! Why, that is not the woman we foundwhen we first entered this place--but another. Where is the fair girl?"
"There's no fair girl," answered the detective Boyd, as all started backin surprise at my astounding assertion. "This is the woman we found,you must be mistaken."
"No," Patterson declared in the low, hoarse voice of one filled withfear. "There is no mistake. When we first entered there was anotherwoman here, younger, prettier, with light hair and blue eyes.
This isthe most unaccountable, most amazing and most inexplicable of all ourdiscoveries."
CHAPTER FIVE.
THE SECOND WOMAN.
The statement that the woman found by Patterson on his first entrythere, and seen by me afterwards, had disappeared, was at firstdiscredited by our companions. It seemed too astounding to be thetruth, nevertheless there was now reclining in the same armchair a womanwho certainly bore no resemblance whatever to the beautiful, fair-hairedgirl with eyes of such deep, pure blue--those eyes that had stared at meso horribly in the ghastly rigidity of death. I recollected that