"You forget, my dear Lloyd," he said.

"Forget what?"

"You forget," Paul went on--"ah, you forget the shadow."

I saw Lloyd's face drop, but he answered sneeringly, "I can carry a sunshade, you know." Then he turned suddenly and fiercely upon him.

"Look here, Paul, you'll keep out of this if you know what's good for you."

A rupture seemed imminent, but Paul laughed good-naturedly. "I wouldn't lay fingers on your dirty pigments. Succeed beyond your most sanguine expectations, yet you will always fetch up against the shadow. You can't get away from it. Now I shall go on the very opposite tack. In the very nature of my proposition the shadow will be eliminated--"

"Transparency!" e.j.a.c.u.l.a.t.ed Lloyd, instantly. "But it can't be achieved."

"Oh, no; of course not." And Paul shrugged his shoulders and strolled off down the briar-rose path.

This was the beginning of it. Both men attacked the problem with all the tremendous energy for which they were noted, and with a rancor and bitterness that made me tremble for the success of either. Each trusted me to the utmost, and in the long weeks of experimentation that followed I was made a party to both sides, listening to their theorizings and witnessing their demonstrations. Never, by word or sign, did I convey to either the slightest hint of the other's progress, and they respected me for the seal I put upon my lips.

Lloyd Inwood, after prolonged and unintermittent application, when the tension upon his mind and body became too great to bear, had a strange way of obtaining relief. He attended prize fights. It was at one of these brutal exhibitions, whither he had dragged me in order to tell his latest results, that his theory received striking confirmation.

"Do you see that red-whiskered man?" he asked, pointing across the ring to the fifth tier of seats on the opposite side. "And do you see the next man to him, the one in the white hat? Well, there is quite a gap between them, is there not?"

"Certainly," I answered. "They are a seat apart. The gap is the unoccupied seat."

He leaned over to me and spoke seriously. "Between the red-whiskered man and the white-hatted man sits Ben Wa.s.son. You have heard me speak of him. He is the cleverest pugilist of his weight in the country. He is also a Caribbean negro, full-blooded, and the blackest in the United States. He has on a black overcoat b.u.t.toned up. I saw him when he came in and took that seat. As soon as he sat down he disappeared. Watch closely; he may smile."

I was for crossing over to verify Lloyd's statement, but he restrained me. "Wait," he said.

I waited and watched, till the red-whiskered man turned his head as though addressing the unoccupied seat; and then, in that empty s.p.a.ce, I saw the rolling whites of a pair of eyes and the white double-crescent of two rows of teeth, and for the instant I could make out a negro's face. But with the pa.s.sing of the smile his visibility pa.s.sed, and the chair seemed vacant as before.

"Were he perfectly black, you could sit alongside him and not see him,"

Lloyd said; and I confess the ill.u.s.tration was apt enough to make me well-nigh convinced.

I visited Lloyd's laboratory a number of times after that, and found him always deep in his search after the absolute black. His experiments covered all sorts of pigments, such as lamp-blacks, tars, carbonized vegetable matters, soots of oils and fats, and the various carbonized animal substances.

"White light is composed of the seven primary colors," he argued to me.

"But it is itself, of itself, invisible. Only by being reflected from objects do it and the objects become visible. But only that portion of it that is reflected becomes visible. For instance, here is a blue tobacco-box. The white light strikes against it, and, with one exception, all its component colors--violet, indigo, green, yellow, orange, and red--are absorbed. The one exception is BLUE. It is not absorbed, but reflected. Wherefore the tobacco-box gives us a sensation of blueness. We do not see the other colors because they are absorbed.

We see only the blue. For the same reason gra.s.s is GREEN. The green waves of white light are thrown upon our eyes."

"When we paint our houses, we do not apply color to them," he said at another time. "What we do is to apply certain substances that have the property of absorbing from white light all the colors except those that we would have our houses appear. When a substance reflects all the colors to the eye, it seems to us white. When it absorbs all the colors, it is black. But, as I said before, we have as yet no perfect black. All the colors are not absorbed. The perfect black, guarding against high lights, will be utterly and absolutely invisible. Look at that, for example."

He pointed to the palette lying on his work-table. Different shades of black pigments were brushed on it. One, in particular, I could hardly see. It gave my eyes a blurring sensation, and I rubbed them and looked again.

"That," he said impressively, "is the blackest black you or any mortal man ever looked upon. But just you wait, and I'll have a black so black that no mortal man will be able to look upon it--and see it!"

On the other hand, I used to find Paul Tichlorne plunged as deeply into the study of light polarization, diffraction, and interference, single and double refraction, and all manner of strange organic compounds.

"Transparency: a state or quality of body which permits all rays of light to pa.s.s through," he defined for me. "That is what I am seeking.

Lloyd blunders up against the shadow with his perfect opaqueness. But I escape it. A transparent body casts no shadow; neither does it reflect light-waves--that is, the perfectly transparent does not. So, avoiding high lights, not only will such a body cast no shadow, but, since it reflects no light, it will also be invisible."

We were standing by the window at another time. Paul was engaged in polishing a number of lenses, which were ranged along the sill.

Suddenly, after a pause in the conversation, he said, "Oh! I've dropped a lens. Stick your head out, old man, and see where it went to."

Out I started to thrust my head, but a sharp blow on the forehead caused me to recoil. I rubbed my bruised brow and gazed with reproachful inquiry at Paul, who was laughing in gleeful, boyish fashion.

"Well?" he said.

"Well?" I echoed.

"Why don't you investigate?" he demanded. And investigate I did. Before thrusting out my head, my senses, automatically active, had told me there was nothing there, that nothing intervened between me and out-of-doors, that the aperture of the window opening was utterly empty.

I stretched forth my hand and felt a hard object, smooth and cool and flat, which my touch, out of its experience, told me to be gla.s.s. I looked again, but could see positively nothing.

"White quartzose sand," Paul rattled off, "sodic carbonate, slaked lime, cutlet, manganese peroxide--there you have it, the finest French plate gla.s.s, made by the great St. Gobain Company, who made the finest plate gla.s.s in the world, and this is the finest piece they ever made. It cost a king's ransom. But look at it! You can't see it. You don't know it's there till you run your head against it.

"Eh, old boy! That's merely an object-lesson--certain elements, in themselves opaque, yet so compounded as to give a resultant body which is transparent. But that is a matter of inorganic chemistry, you say.

Very true. But I dare to a.s.sert, standing here on my two feet, that in the organic I can duplicate whatever occurs in the inorganic.

"Here!" He held a test-tube between me and the light, and I noted the cloudy or muddy liquid it contained. He emptied the contents of another test-tube into it, and almost instantly it became clear and sparkling.

"Or here!" With quick, nervous movements among his array of test-tubes, he turned a white solution to a wine color, and a light yellow solution to a dark brown. He dropped a piece of litmus paper into an acid, when it changed instantly to red, and on floating it in an alkali it turned as quickly to blue.

"The litmus paper is still the litmus paper," he enunciated in the formal manner of the lecturer. "I have not changed it into something else. Then what did I do? I merely changed the arrangement of its molecules. Where, at first, it absorbed all colors from the light but red, its molecular structure was so changed that it absorbed red and all colors except blue. And so it goes, ad infinitum. Now, what I purpose to do is this." He paused for a s.p.a.ce. "I purpose to seek--ay, and to find--the proper reagents, which, acting upon the living organism, will bring about molecular changes a.n.a.logous to those you have just witnessed. But these reagents, which I shall find, and for that matter, upon which I already have my hands, will not turn the living body to blue or red or black, but they will turn it to transparency. All light will pa.s.s through it. It will be invisible. It will cast no shadow."

A few weeks later I went hunting with Paul. He had been promising me for some time that I should have the pleasure of shooting over a wonderful dog--the most wonderful dog, in fact, that ever man shot over, so he averred, and continued to aver till my curiosity was aroused. But on the morning in question I was disappointed, for there was no dog in evidence.

"Don't see him about," Paul remarked unconcernedly, and we set off across the fields.

I could not imagine, at the time, what was ailing me, but I had a feeling of some impending and deadly illness. My nerves were all awry, and, from the astounding tricks they played me, my senses seemed to have run riot. Strange sounds disturbed me. At times I heard the swish-swish of gra.s.s being shoved aside, and once the patter of feet across a patch of stony ground.

"Did you hear anything, Paul?" I asked once.

But he shook his head, and thrust his feet steadily forward.

While climbing a fence, I heard the low, eager whine of a dog, apparently from within a couple of feet of me; but on looking about me I saw nothing.

I dropped to the ground, limp and trembling.

"Paul," I said, "we had better return to the house. I am afraid I am going to be sick."

"Nonsense, old man," he answered. "The sunshine has gone to your head like wine. You'll be all right. It's famous weather."

But, pa.s.sing along a narrow path through a clump of cottonwoods, some object brushed against my legs and I stumbled and nearly fell. I looked with sudden anxiety at Paul.

"What's the matter?" he asked. "Tripping over your own feet?"

I kept my tongue between my teeth and plodded on, though sore perplexed and thoroughly satisfied that some acute and mysterious malady had attacked my nerves. So far my eyes had escaped; but, when we got to the open fields again, even my vision went back on me. Strange flashes of vari-colored, rainbow light began to appear and disappear on the path before me. Still, I managed to keep myself in hand, till the vari-colored lights persisted for a s.p.a.ce of fully twenty seconds, dancing and flashing in continuous play. Then I sat down, weak and shaky.

"It's all up with me," I gasped, covering my eyes with my hands. "It has attacked my eyes. Paul, take me home."

But Paul laughed long and loud. "What did I tell you?--the most wonderful dog, eh? Well, what do you think?"