Methyltrichlorosilane, CH3SiCl3: a colourless liquid with a sharp smell like hydrochloric acid, boiling at about 66 °C. Passed over plain hot silicon, methyl chloride gives mostly this compound (52 % in Rochow's 1945 example); with today's copper catalyst it is the second product (5–15 %), after dimethyldichlorosilane. Water turns it into cross-linked methyl silicone resin.