The Narrow Cell. Ronal Kayser

losangelensis.

      “If you would only ask me,” said she. “There are 824 pages of text.”

      And very luxurious pages they were, being printed on enamelled stock and bound in three-quarters calfskin.

      “You’re just looking at the pictures!” said she some moments later.

      “No . . . These tables of chemical analysis. Did you do all that by yourself?”

      “Of course!” said Darwina with almost Amazonian indignation. “Do you suppose I hired a ghost to do my research for me?”

      Kenmore had not supposed anything of the kind; as a matter of fact, he had not known what he would find in the famous monograph. The only marine research that had ever interested him was the behavior of a swordfish or yellowtail on the end of several hundred yards of deep-sea line. The solid scientific reputation of the monograph had made him fight shy of ever peeping inside its calfskin covers. He felt if it had been comprehensible to a layman, it wouldn’t have been scientific.

      “It seems you are a practical chemist,” said he abruptly. “You should make an excellent substitute for our police test tube expert who is going into the Army and can’t possibly be present to testify at the trial. If there ever is a trial.”

      “I don’t know that I want to testify at a trial . . .”

      “Of course you don’t. But you will, my model citizen.”

      Darwina colored. “Well-1, if it is really necessary.”

      “It is absolutely necessary . . . You have a key to the Institute laboratory, haven’t you?”

      The key let them into a dark and cavernous tunnel of hallway extending down the middle of the laboratory building. Darwina frowned as her companion drew the envelope from his pocket.

      Kenmore said: “Here’s the exhibit. It’s been fingerprinted and photographed in its original condition. Also, I’ve shown it to the family. I didn’t get a nibble. If the thing is authentic, it’s up to me to find that out by other means than confirmatory testimony. It will have to speak for itself, since no one of them will identify or explain it. That’s where you, as a chemist, come in.”

      “Whatever do you want me to do with it?” said Darwina uneasily.

      “We’ll begin by making an analysis of the ink.”

      Darwina reached a hand to the doorknob. “Oh, no, we won’t. I won’t. I know my limitations—”

      “It will be only an elementary analysis,” said the detective. “I suppose it is ordinary, blue-black gallotannic ink. That is, it is probably a sulphuric or hydrochloric solution of tannic and gallic iron salts in combination with an additional aniline dye, sugar, gum arabic, and so on. As you know, the blue in ink doesn’t actually turn black. It is the aniline dye which is blue, and the iron salts which in time are oxidized and cause the writing to blacken.”

      “Yes,” said Darwina. “I knew that, but I never knew-chemistry was one of your hobbies.”

      “It isn’t. I once had a case involving an altered will, and so I had to bone up on the identification of inks.

      “Well,” Kenmore said, “this is black ink. And if it is black owing to oxidation, that can be proved by making a test for iron salts.”

      “Hydrochloric solution of ferrocyanide and rhodanid of sodium in nitric acid,” nodded Darwina, “but I suppose there is no use telling you that.”

      “It is no use telling me. I know the theory of the thing. It’s the practical technical touch I lack.”

      Darwina led the way along the hall to a large room equipped with work benches, concrete vats, and racks of retorts and test tubes. She slid her arms into a rubberized apron, helped herself to a supply of chemicals from a cabinet, and set to work.

      “Well?” said the lieutenant presently.

      Darwina looked up from the eyepiece of a Spencer microscope. “There is an iron reaction,” she reported.

      Some of the tension relaxed on Kenmore’s angular features.

      “It is gallotannic ink, then,” said he, “and we can plunge it into Ermel’s solution.”

      “What’s that?”

      He opened his pocket memo book.

      “You make up five grams of silver nitrate, one gram of citric acid, half a gram of tartaric acid, and three drops of nitric acid in a hundred grams of distilled water . . . You have a photographic darkroom in the building? This has to be used under a ruby light.”

      “Yes, but what is it for?”

      “You will see—if Miss Hope put a letter into it. She wasn’t a wasteful person, she always wrote on both sides of a piece of paper,” said Kenmore reminiscently.

      “The darkroom is down in the basement.”

      There followed an interval of activity under the darkroom’s ruby light (in the course of which the envelope got slit open).

      Some minutes later:

      “There is writing on it!” cried Darwina.

      “It is not writing. It’s a latent image, a picture, that is transferred from one piece of paper to another if they are brought in contact, and if one piece has been written upon with gallotannic ink. Don’t ask me why,” Kenmore forestalled hurriedly. “I am not chemist or physicist enough to understand the phenomenon, but it is so. Criminologists have been getting evidence out of discarded envelopes for years, but it is not very likely a forger who prepared a plant like this would think to prepare a forged enclosure as well.”

      “Unless it was to fool Henry Bowling,” said Darwina.

      “Yes. In that case, it will be helpful to. know how he was fooled.

      “Only,” unhappily, “of course it is not possible to recover more than a fragment—the portion of the letter that was in direct contact with the envelope surface.”

      Darwina bent closer to the developing tray. “I can’t read it at all, it is backwards—no. It is like a blotter impression. You hold it up to a mirror.”

      “We’ll have Heyes photograph it first,” said Kenmore. “Because in the fixing bath the image is very apt to fade.”

      Fascinated, Darwina peered into the tray. “. . . a-n-d s-a-y-s period H-e i-s a b-o-s-t-o-,” and paused. “No. B-a-s-t-a-r-d. Well! I must say I am surprised at her language!”

      Catherine Hope, in fact (if in fact it was she) had written:

      . . . and says. He is a bastard but of c .... e I don’t let on all I….ow. . .n’t you either. You had better burn this and fo……ver told you. I have not got any work.... ll week on... nt of it. I tore up my... irst letter but then tho…..know in case anyth……pens to me, destroy it for his wife’s sake.

      Has……..ing sister,

      KATIE

      “But!” cried Darwina. “Whatever was the rest of it?”