1427767 Microscopes; pyrolysis samples COMPAGNIE FRANCAISE DES PETROLES 17 Dec 1973 [21 Dec 1972] 58407/73 Heading G2J Apparatus for the analysis of a microscope specimen by pyrolysis comprises an optical microscope 1, an ocular tube 56 connecting a laser 3 to the microscope, and an hermetic chamber on the platform 2 in which pyrolysis is effected and which is connectible to a supply of gas 7 for entraining the pyrolysis products and to a chromatograph 13. The microscope includes a total reflection prism movable e.g. by button 57 between a position for viewing the specimen and a retracted position for allowing direct passage of the laser beam to the specimen. The hermetic chamber (50) Fig. 6 comprises a ring 24 which has a seating 43 for a window 25 and a groove 49 in the base for an O-ring 48. An inlet port is provided for admitting gas e.g. helium from supply 7 and an exit port 51 is provided for the helium/pyrolysate mixture. In use, the ring 24 is urged downwardly against a microscope slide (not shown) to which is stuck a section of the specimen. The point of the specimen to be analyzed is then determined by viewing through the microscope after which the totally reflecting prism is retracted and emission of the laser beam is started by operation of the high voltage supply 5 while the chamber 50 is scavenged by the gas from 7.