Cum Grano Salis Page 6

ofmagnesia, different things."

  Smathers looked disappointed, but before he could say anything, Dr.Petrelli's awed but excited voice came from behind him. "Do you takeEpsom salts?"

  "Yeah."

  "I wonder--" said Petrelli softly.

  And then he left for the lab at a dead run.

  * * * * *

  Colonel Fennister and Major Grodski sat at the table in the lab,munching on banana-pears, blissfully enjoying the sweet flavor and thefeeling of fullness they were imparting to their stomachs.

  "MacNeil can't stay in the service, of course," said Fennister. "Thatis, not in any space-going outfit. We'll find an Earthside job for him,though. Maybe even give him a medal. You sure these things won't hurtus?"

  Dr. Pilar started to speak, but Petrelli cut him off.

  "Positive," said the chemist. "After we worked it out, it was prettysimple. The 'poison' was a chelating agent, that's all. You saw the testrun I did for you."

  The colonel nodded. He'd watched the little chemist add an iron salt tosome of the fruit juice and seen it turn red. Then he'd seen it turnpale yellow when a magnesium salt was added. "But what's a chelatingagent?" he asked.

  "There are certain organic compounds," Dr. Petrelli explained, "that are... well, to put it simply, they're attracted by certain ions. Some areattracted by one ion, some by another. The chelating molecules clusteraround the ion and take it out of circulation, so to speak; theyneutralize it, in a way.

  "Look, suppose you had a dangerous criminal on the loose, and didn'thave any way to kill him. If you kept him surrounded by policemen allthe time, he couldn't do anything. See?"

  The Space Service Officers nodded their understanding.

  "We call that 'sequestering' the ion," the chemist continued. "It's usedquite frequently in medicine, as Dr. Smathers will tell you. Forinstance, beryllium ions in the body can be deadly; beryllium poisoningis nasty stuff. But if the patient is treated with the proper chelatingagent, the ions are surrounded and don't do any more damage. They'restill there, but now they're harmless, you see."

  "Well, then," said the colonel, "just what did this stuff in the fruitdo?"

  "It sequestered the iron ions in the body. They couldn't do their job.The body had to quit making hemoglobin, because hemoglobin needs iron.So, since there was no hemoglobin in the bloodstream, the patientdeveloped sudden pernicious anemia and died of oxygen starvation."

  Colonel Fennister looked suddenly at Dr. Smathers. "I thought you saidthe blood looked normal."

  "It did," said the physician. "The colorimeter showed extra hemoglobin,in fact. But the chelating agent in the fruit turns red when it'sconnected up with iron--in fact, it's even redder than blood hemoglobin.And the molecules containing the sequestered iron tend to stick to theoutside of the red blood cells, which threw the whole test off."

  "As I understand it, then," said Major Grodski, "the antidote for the... uh ... chelating agent is magnesium?"

  "That's right," said Dr. Petrelli, nodding. "The stuff prefers magnesiumions to ferrous ions. They fit better within the chelating ring. Anysource of magnesium will do, so long as there's plenty of it. MacNeilwas using milk of magnesia, which is the hydroxide, for 'gastricacidity'. It's changed to chloride in the stomach. And he was usingEpsom salts--the sulfate, and magnesium citrate as laxatives. He waswell protected with magnesium ions."

  "We tried it ourselves first, naturally," said Dr. Pilar. "We haven'thad any ill effects for two days, so I think we'll be able to make ituntil the ship comes."

  Major Grodski sighed. "Well, if not, I'll at least die with a fullstomach." He reached for another banana-pear, then looked over atPetrelli. "Pass the salt, please."

  Silently and solemnly, the chemist handed him the Epsom salts.

  THE END

  +--------------------------------------------------------------+ | Transcriber's Note and Errata | | | | This etext was produced from Astounding Science Fiction, May | | 1959. Extensive research did not uncover any evidence that | | the U.S. copyright on this publication was renewed. | | | | The following typographical errors were corrected: | | | | |Error |Correction | | | |catastrophies |catastrophes | | | |Phenacitin |Phenacetin | | | |Caffiene |Caffeine | | | |stacatto |staccato | | | |phosphorpus |phosphorus | | | |charteuse |chartreuse | | | |dizzness |dizziness | | | |MacNeal |MacNeil | | | | | A few subscripted numbers have been formatted preceded by an | | underscore, e.g., B_12. | +--------------------------------------------------------------+