seguin’s eudiometer.

22 §

Take a glass cylinder closed at the top, and whose capacitymust be measured into sufficiently small portions by a graduatedscale fixed on it. If the instrument be destined solely for ex-amining atmospheric air, it will be sufficient to apply the scalefrom the orifice of the cylinder down to about half its length, orto sketch that scale on a slip of paper pasted on the outside of thetube, and to varnish it over with a transparent varnish.

This half of the eudiometrical tube is divided into fifty equi-distant parts, which in this case indicate hundredth parts of thewhole capacity of the instrument.

Into this vessel full of atmospheric air put a piece of dry phos-phorus (one grain to every twelve cubic inches) close it air-tightand heat it gradually, first the sides near the bottom and after-wards the bottom itself. The phosphorus will take fire and bumrapidly. After every thing is cold, invert the mouth of the eu-diometer-tube into a bason of water or mercury, and withdrawthe cork. The water will ascend in proportion to the loss of ox-igen gas the air has sustained, and thus its quantity may be as-certained.

Analogous to this is

5. SEGUIN's EUDIOMETER,

Which consists of a glass tube of about one inch in diameter,and eight or ten inches high, closed at the upper extremity. Itis filled with mercury and kept inverted in this fluid in the. mer-curial trough. A small bit of phosphorus is introduced into it,which on account of its specific gravity being less than that ofmercury, will rise up in it to the top. The phosphorus is thenmelted by means of a red-hot poker, or burning coal applied tothe outside of the tube. When die phosphorus is liquified, smallportions of air destined to be examined, and which have beenpreviously measured in a vessel graduated to the cubic inch or intograins, are introduced into die tube. As soon as the air which

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