G26 SUMMARY OF CURRENT RESEARCHES RELATING TO 



alcohol, since objects may be mounted in it directly from 95 p.c. alcohol. 

 It dries rapidly, so that preparations may be studied with safety at the 

 end of twenty-four hours. Cover-slips may be removed from old pre- 

 parations by immersion in 95 p.c. alcohol for several hours. Another 

 useful property of euparal is its low index of refraction, which is well- 

 adapted to cytological study, giving a much-desired increase of visibility 

 to delicate elements. Another important feature is that it does not 

 bleach the stain. 



(6) Miscellaneous. 



Development of Botanical Microtechnique.* — G. M. Smith 

 describes the development of botanical microtechnique under the follow- 

 ing captions. 1. The methods of the early microscopists (from the time 

 of Hooke's discovery of the cell to 1800). 2. The technique of the 

 English microscopists (1800-1875). 3. The methods of the German 

 botanists (1800-1875). 4. The development of modern methods of 

 microtechnique (1875 to the present). There is much useful informa- 

 tion in the article which deserves the perusal of those interested in the 

 historical aspects of microscopy. A copious bibliography is appended. 



Metallography, etc. 



Copper-tin Alloys. f — J. L. Haughton has studied the constitution 

 of the copper-tin alloys in the range 55 to 65 p.c. tin, which is the 

 range containing the € constituent. The alloys were cast in a wedge- 

 shaped mould made of thin sheet copper, surrounded by a freezing 

 mixture. The very rapid solidification and cooling produced a fine 

 structure which on subsequent annealing attained equilibrium in much 

 less time than that required for alloys which had been cooled less 

 rapidly. Specimens were annealed for 20 to 300 hours at 210°, 310°, 

 and 390° C, quenched, and examined microscopically. At 59 p.c. tin 

 the alloy annealed at 390° C. consisted of pure e. With less tin -q was 

 also present, and with more tin the annealed alloy consisted of € + 

 eutectic. After annealing at 310° C. pure e contained 59*5 p.c. tin. 

 At 210° C. the composition of pure e is between 59 "8 and 61 p.c. tin. 

 In all specimens containing any quantity of eutectic the e was not 

 coloured by the etching reagent used (ferric chloride in hydrochloric 

 acid), while in the absence of the eutectic it etched dark, leaving the 77 

 as pale blue crystals. This formed a sensitive test for the presence of 

 eutectic. Heating curves were taken. The author's conclusions are 

 embodied in an equilibrium diagram for the range studied. 



Microstructure of Base-metal Thermocouples.} — O. L. Kowalke 

 has microscopically examined transverse sections of thermocouple wires, 

 annealed at various temperatures. Pure metals, or alloys consisting of 



* Trans. Amer. Micr. Soc, xxxiv. (1915) pp. 71-129 (3 pis. and 12 text figs.). 

 f Journ. Inst. Metals., xiii. (1915, 1) pp. 222-48 (30 figs.). 



j Trans. Amer. Electrochem. Soc, xxvi. (1914) pp. 199-214, through Science 

 Ahstracts, xviii. (1915) pp. 372-3. 



