144 



Mr. W. N. Hartley on the 



[Feb. 8, 



slightly acidified with tartaric acid. It was found that in no case should 

 filtering be resorted to if possible, as the finest Swedish paper transfers 

 myriads of its fibres to the liquid. Paper of nitro-cellulose (that is to say, 

 Swedish filter-paper treated with a mixture of sulphuric and nitric acids) is 

 disintegrated to a less extent than ordinary paper ; and it is possible that, 

 for special purposes, it might be of service in filtering a liquid so as to 

 render it clear of fine particles, though no filtration will thoroughly clear 

 a liquid. With proper care, however, filtration is unnecessary when deal- 

 ing with solutions of definite salts. 



On July 15th, 1870, a tube was half-filled with the above 5 per cent, 

 solution of the mixed salts, and exhausted by the Sprengel. On trying 

 whether it acted as a water-hammer on the following day the tube was split 

 into fragments. The tubes require very careful handling, as the pointed 

 ends give way readily. 



July 1 b'th, 1870. — Three other tubes were sealed up with the same liquid, 

 the exhaustion in each case being perfect. The glass was heated to red- 

 ness before introducing the liquid. After heating to 150° C. for four hours 

 (during a few minutes the temperature accidentally rose to 180°), the tubes 

 in a perpendicular position were placed at rest on a shelf, where the tem- 

 perature was about 25° C. 



Exp. I. The liquid, at first clear, after the lapse of three days had depo- 

 sited flocculi. On October 7th one of the tubes was opened in the apparatus, 

 and with the care already described. The gelatinous matter, on examination 

 by a microscope magnifying 400 diameters, showed no signs of organization 

 or structure of any kind. A small quantity was collected on a very small 

 Swedish filter, and removed by means of a small platinum spatula. On 

 heating it did not char, and was therefore inorganic matter ; the usual blow- 

 pipe tests showed it to be silica. The disodic phosphate had attacked the 

 glass; the silica deposited on standing, and hence the jelly-like mass. The 

 remainder of the liquid was examined, but no trace of an organism could be 

 detected. This tube had been kept exactly 84 days, during which time its 

 temperature ranged between 18° and 25° C. 



On July 21st, 1870, three other tubes containing freshly prepared am- 

 monium tartrate and sodium phosphate were sealed up, the liquid being 

 simply boiled to expel air; these were heated to 110°C. for three hours. 

 Range of temperature 18° to 25° C. 



Exp. II. No. 1 was opened October 7th, and examined with the same 

 microscopic power. No living organism, and no trace of organic matter 

 even, beyond a cotton-fibre and one or two small patches of indefinite and 

 shapeless matter, which came from the solid residue of the liquid adhering 

 to the glass within the capillary tube being charred in the act of sealing up. 

 Several drops of liquid were examined at the lower point, the centre, and 

 the surface, with the above results in the first case, but in the latter portions 

 the liquid was absolutely clear. This tube had been kept 78 days. 



Exp. III. No. 2, July 21st, 1870. Tartrate of ammonia and phosphate 



