fT M 34 QUANTITATIVE AGRICULTURAL ANALYSIS The nickel grid through which the mixture flows at the top of the burner causes the gas to burn exactly as though each mesh were a small individual burner. The tip of the inner reducing cone of each small flame is usually about one millimeter above the top of the burner and, as all of the small flames unite to form one large one, the result is a highly concentrated flame, every part of which is oxidiz- ing in character except a zone of about one millimeter in depth, immediately above the top of the burner. This is a distinct advantage, especially in heating platinum articles, since platinum is easily dam- aged by heating in a reduc- ing flame. A number of imitations and modifications of the M6ker burner are offered for use at this time. Most of these use the same combus- tion principle, the burners differing only in mechanical features. Blast Lamp.—In order to produce a higher temperature a burner may be constructed so as to consume a larger quantity of gas, depending for its complete combustion upon admission of air under pressure. A burner so con- structed is called a "blast lamp." Many forms of such burners are in use. The flame of the M£ker burner is nearly as hot as that of the ordinary blast lamp using the same gas and it may be substi- tuted for the blast lamp in many cases. There is also a M£ker blast lamp, similar in construction to the one already described but using air under pressure. FIG. 14.—Section of M£kcr burner.