TEANSACTIONS OF THE SECTIONS. 37 



By this simple method the greatest refinement may he attained. Of course, care 

 must be taken to have the baryta- or lime-water perfectly clear to begin with. 

 The author said he had not used these methods for purely scientific investigations. 



On a Apparatus for the Determination of the Ozone in the Atmosphere, and 

 Experiments made therewith by means of the Aspirator. By John Smyth, 

 Jun., A.M., Mem. B.M.S. 



The author being interested in linen bleaching, took daily meteorological obser- 

 vations for several years, in which be directed particular attention to ozone. He 

 found the usual methods of testing its presence in the atmosphere unsatisfactory, 

 and showed it is so by reference to a Diagram Chart of all the elements of the 

 weather in 1864, prepared by him. He was therefore led to devise an apparatus, 

 the principle of which is, by means of a large aspirator, to draw the air at a con- 

 siderable velocity through a small tube, so as to impinge at its opening into a tube 

 of larger diameter against an extended surface of test-paper. This ozonometer 

 consists of two brass or opaque glass tubes or boxes about 2 inches long and 2 inches 

 in external diameter, the smaller of which screws or fits tightly into the larger, 

 and is about £th of an inch shorter ; its extremity at the point of the screw is 

 grooved for an india-rubber band which holds the test-paper stretched across its 

 mouth. The entrance-tube, |th inch in diameter, is introduced into the centre of 

 the solid extremity of the larger box, |th of an inch from the centre of the test- 

 paper. A small pipe from the solid extremity of the smaller box communicates 

 with the aspirator, which the author prefers should be made on the plan of Dr. 

 Andrews, of Queen's College, Belfast, viz., a gasometer of a capacity of about 

 80 gallons, connected by means of a cord to a clock in which an extra weight is 

 slung, which raises the gasometer at a uniform velocity over which the pendulum 

 gives complete control. A counterpoise is used to support the weight of the 

 gasometer. The author showed, from a table of experiments made by this im- 

 proved ozonometer, that there is not much difference in the quantity of sensible 

 ozone in two masses of air of equal volume, moving at different velocities, in differ- 

 ent directions, and under different hygrometrical conditions. Also that the test- 

 papers in the ordinary ozone-cage do not register high enough ; a more extended 

 series of experiments may, however, somewhat modify these views. 



On Phosphatic Deposits recently discovered in North Wales. 

 By Dr. Aug. Voelcker. 



An extensive mine, containing several phosphatic minerals, was accidentally dis- 

 covered last year by Mr. Hope Jones, of Hooton, Cheshire, whilst he was searching 

 for other minerals in the neighbourhood of Cwmgynen, about sixteen miles from 

 Oswestry. 



The mine is continuous for more than nine miles, and occurs 12 feet under the 

 surface. 



It is not far from the clay-slate and lead-bearing district of Llangyno"-. 



The strata (slaty shale) contain several beds of contemporaneous* felspathic ash 

 and scoriae, and the usual fossils of the Llandeilo series are found, but not in great 

 numbers. 



The strata are vertical, and run east to west, or, more correctly speaking, 15 

 degrees north of west (magnetic). 



A true vein or fissure containing vein deposit, partially metallic, divides two 

 phosphatic deposits. 



One of them is nearly 3 yards in thickness, and embodies phosphatic limestone 

 beds, containing from 10 to upwards of 35 per cent, of phosphate of lime. 



The other and more valuable deposit is a yard and a half thick, and consists of 

 a black graphitic shale, largely impregnated with phosphate of lime. 



This deposit is free from carbonate of lime, and much richer in phosphate of 

 lime than the first-mentioned deposit. 



In specimens taken at a depth of about 12 feet from the surface, Dr. Voelcker 

 found from 54 to 56 per cent, of phosphate of lime in this phosphatic shale. 

 - At a greater depth the shale becomes richer in phosphates, and consequently 



