The difficulty would appear to be rather that of directly and quickly reaching the seat of the fire, than of the more or less fire-quenching properties of rival fluids. From the evidence of Mr. John F. Dane at the Cripplegate Fire Enquiry, we may gain some idea why the brigade dislike the chemical fire-engine. He had been twenty-eight years in the brigade--though he had then left the service, and was a consulting fire engineer--but at one fire, where he had found a dense smoke, an hour was occupied in tracing the fire to its source, it being worked upon by hand-buckets. Had he used a chemical fire-engine, it would, no doubt, have been played into the dense smoke, and damaged a thousand pounds' worth of goods, while, after having exhausted the charge, they would not have found the fire subdued. Chemical fire-engines could not be trusted to discharge where wanted. Many modern structures at the Cripplegate fire were comparatively frail. Iron girders and stone were, no doubt, largely used, and you would naturally think that iron would be fireproof; but, as a matter of fact, iron may be worse than wood. That is, cast-iron is very liable to split, if suddenly heated or cooled; and a jet of water playing on a hot cast-iron girder would most likely cause it to collapse at once, and bring down everything it supported in a terrible ruin. The truth is, therefore, that light iron and stone structures are not nearly so fireproof as they might appear. The difficulty of building fireproof structures has not yet been fully solved, though many suggestions to that end have been made. Wood soaked in a strong solution of tungstate or silicate of soda is rendered uninflammable and nearly incombustible. Silicate of soda is, perhaps, the best. It fuses in the heat, and forms a glaze over the wood, preventing the oxygen in the air from reaching it. But intense heat will overcome it. Whichcord's plan of fire-proofing encases metal girders in blocks of fire-clay; other systems make great use of concrete. Walls, of course, should be built of brick or stone; while double iron doors are of great value, as in the case of the warehouses burning at the docks on January 1st, 1866.