p&c.brimstone-第24部分
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Dienphong nodded toward his assistant and the lights dimmed。 He switched on the puter projector。
〃Please feel free to interrupt with questions at any time。〃 He called up the first image。 〃We'll go from simplest to most plex。 This is a 50x sample of the sulfur recovered at the site。 Our chemical analysis showed it to be natural； with trace elements that indicate a volcanic origin。 It had been rapidly heated and burned by unknown means。 When sulfur burns； it bines with oxygen to make sulfur dioxide gas； SO2； which has a very strong odor…the smell of burned matches。 If it then es in contact with water； it creates H2SO4； also known as sulfuric acid。
〃These fibers here〃 …the next image came up…〃are from the victim's clothing。 Note the pitting and curling： clear effects of sulfuric acid on the victim's clothes。〃
Three more images in quick succession。 〃As you can see； there was even microscopic pitting on the victim's plastic glasses； and in the varnish on the walls and floor； from the intense release of sulfur pounds。〃
〃Any idea of the specific volcanic source？〃 It was Pendergast who spoke。
〃That's almost impossible to answer。 We'd have to analyze and pare this with thousands of known volcanic sources； an overwhelming job even if we could get the samples。 What I can tell you is that the high proportion of silicon indicates a continental； as opposed to an oceanic； source。 In other words； this sulfur didn't e from Hawaii or； say； the seafloor。〃
Pendergast settled back； his expression unreadable in the dark room。
〃This next image shows some microsections of the burned wood of the floor from the so…called hoofprint。〃 Several more images flashed across the screen。 Dienphong cleared his throat。 Here is where the difficulties began。
〃You will note the very deep penetration of the burn into the wood。 You can see it better at 200x。〃
Another slide。 〃This was not caused by a 'branding iron' effect。〃 He paused； swallowed。 〃That is to say； this mark was not burned into the floor by a red…hot object being impressed into the wood。 It was caused by an intense burst of nonionizing radiation； probably in the very short infrared wavelength range； which deeply penetrated the wood。〃
Carlton spoke up； as Dienphong knew he would。 〃You mean； the perp didn't heat something up and press it on the wood？〃
〃Exactly。 Nothing actuallytouched the wood。 The burn was made by a short blast of pure radiation。〃
Carlton shifted； the chair uttering a dangerous groan。 〃Wait a minute。 How can that be？〃
〃My job is to describe； not interpret；〃 said Dienphong； flicking up the next slide。
But the chief hadn't finished。 〃Are you saying the mark was made with some kind ofray gun ？〃
〃I can't say what the source of the radiation was。〃
Carlton settled back with a dubious grunt。
〃This brings us to the cross。〃 The next slide came up。 〃Our art expert has identified this as a rare example of a seventeenth…century Tuscan cross； monly worn by the noble classes。 It is made of gold and silver； layered； fused； and hand…chased to produce a rather interesting effect known aslamellés fines 。 It was then set in wood； which has largely burned away。〃
〃How much's it worth？〃 Carlton said； asking an intelligent question for a change。
〃Given the precious stones； eighty； perhaps one hundred thousand dollars。 Undamaged； that is。〃
Carlton whistled。
〃The cross was found around the neck of the victim； touching his skin。 Here is a photograph of it at the scene of the crime； still around the victim's neck。〃
The next slide came up； prompting noises of disgust and disbelief。
〃As you can see； the cross heated to the point of melting； deeply burning the skin where it lay。 But observe that the surrounding flesh is not scorched or even reddened。 Something…and I really can't say what…selectively heated the crosswithout heating the surrounding skin。 The cross then partially melted and burned itself into the victim's flesh in situ。
〃And here〃…he brought up the next image…〃is an electron micrograph at 3；000x； showing this extraordinary pitting along the silver…butnot the gold…surface of the cross。 I can't account for this； either。 I suspect it might have been caused by an intense and prolonged dose of radiation that seems to have stripped off the top layers of electrons and vaporized part of the metal。 It acts much more strongly on silver than on gold。 Again； I have no idea why。〃
Carlton was on his feet。 〃Can we have this in plain English？〃
〃Of course；〃 Dienphong said dryly。 〃Something heated up and melted the cross without heating up anything around it。 I guess it must have been some kind of radiation that was taken up by metal more strongly than flesh。〃
〃Like maybe the same radiation that burned the hoofprint？〃
Carlton ； Dienphong had to admit； was not as stupid as he pretended to be。
〃A good possibility。〃
Pendergast raised a finger。
〃Agent Pendergast？〃
〃Were there any signs of radiation burns or heating in any other surfaces in the room？〃
An even better question。 〃Yes； in fact； there were。 The bedposts； which were varnished pine； showed signs of heat stress； as did the wall behind the bed； which was painted pine。 In some areas； the paint had softened and bubbled。〃
He moused his way through the on…screen menu and pulled up another image。 〃Here's a cross section of the wall； showing four layers of paint。 Now here's yet another small mystery： only thelowest layer of paint seems to have heated up and bubbled。 The others were undisturbed and remained chemically unaltered。〃
〃Did you analyze all four layers of paint？〃 Pendergast asked。
Dienphong nodded。
〃Was the bottom layer a lead…based paint？〃
Dienphong felt a sudden surprise。 He quickly saw where the line of questioning would lead； and it was something that he had not thought of。 〃Let me check the book。〃 He flipped through the lab reports； organized and categorized in a three…ring binder labeledBrimstone 。 All FBI investigations get a nickname； and this was the one he had given this case。 Melodramatic； perhaps； but appropriate。
He looked up from the binder。 〃Yes； as a matter of fact it was lead…based。〃
〃And the rest were not？〃
〃That's correct。〃
〃Further proof that we are dealing with some kind of radiation。〃
〃Very good； Agent Pendergast。〃 It was the first time in his career that an FBI agent had beaten him to a conclusion。 This Pendergast was living up to his reputation。 Dienphong cleared his throat。 〃Any other questions or ments？〃
Carlton sat down again； raised a weary hand。
〃Yes？〃
〃I'm missing something。 How could something affect thebottom layer of paint and not the upper ones？〃
Pendergast turned。 〃It was thelead in the paint that reacted； like the metal in the cross。 It absorbed the radiation more strongly。 Was there any radioactivity present at the site； Doctor； during follow…up investigation？〃
〃None whatsoever。〃
Carlton nodded。 〃Check into that； Sam； will you？〃
〃Of course； sir；〃 one of the junior agents replied。
Dienphong went to the next image。 〃Here's the final image： a close…up of a section of the cross。 Note the very localized melting； pletely inconsistent with a convective source of heat。 Again an indication that radiation played a role。〃
〃What type of radiation would selectively heat metal more than flesh？〃 Pendergast asked。
〃X…rays； gamma rays； microwave； far infrared； certain wavelengths in the radio spectrum； not to mention alpha radiation and a flux of fast neutrons。 This is not very unusual。 What is unusual is theintensity 。〃
Dienphong waited for the inevitable expostulation from Carlton； but this time the agent in charge said nothing。
〃The pitting on the cross；〃 Pendergast said； 〃might suggest to you something？〃
〃Not so far。〃
〃Speculations？〃
〃I never speculate； Mr。 Pendergast。〃
〃An intense electron beam could cause it； don't you think？〃
〃Yes； but an electron beam would have to propagate through a vacuum。 Air would disperse it in； say； a millimeter or two。 As I said； it might have been in the infrared； microwave； or X…ray spectrum； except that it would take a transmitter of several tons to generate a beam that intense。〃
