250 APPENDIX 1. 



Dr. AV. H. Hatfield. — Photomicrographs ilhistrating applica- 

 tion of microscope to metallurgical work. 



Mr. E. Hatschek. — Ultra-filters for retaining ultra-microscopic 

 particles. Collodion membrances are used as septa : according to 

 the method of preparation they may be used with pressure (Bechhold) 

 or they may work with hydrostatic head only (Wo. Ostwald). 



Messrs. Hawksley and Sons. — Microscopes by the Spencer 

 Lens Company suitable for research work, students' models, also 

 travelling moclel in all-metal case. Blood examination apparatus. 

 Thoma-Hawksley haemacytometers with various rulings. 



Mr. C. F. Hill and Mr. H. C. Lancaster. — The use of the 

 microscope in the metallography of lead. Typical samples of lead, 

 containing antimony, tin, copper, and zinc. Also a new bearing 

 metal, made of lead, containing calcium and barium. 



Miss Nina Hosali. — Models illustrating crystalline form and 

 symmetry. 



Messs. Ilford, Ltd. (Mr. F. F. Renwick). — Exhibit arranged 

 to show the range and spectrum of thirty colour filters, including 

 a set of nine micro-filters, eight spectrum (single-band) filters, tri- 

 colour filters and their complementaries, mercury vapour lamp filters 

 and photographic correction filters. 



Jaeger Laboratory (Mr. A. E. Garrett). — • 



Exhibit Illustrating the Analysis of Textiles. 



The microscope is the final Court of Appeal in the testing of 

 textile materials in so far as the nature of their constituent fibres 

 is concerned. 



There is no difficulty in dividing the more generally used fibres 

 into the following distinct classes: — 



1. Wool and other animal hairs. 



2. Silk. 



3. Cotton. 



4. Other plant fibres (flax, ramie, jute, etc.). 



Classes 1 and 4 are, however, as indicated, subject to much 

 subdivision. 



Class 1 contains wool, camel hair, alpaca, vicuna, cashmere, 

 mohair, and a> few less well-known hairs. Class 4 contains all the 

 multi-cellular fibres obtained from the stems or leaves of plants, 

 and their number mounts up considerably, especially if those em- 

 ployed for sacking, rope, etc., are included. 



The distinguishing features in Class 1 are the diameter of the 

 fibres, the colour of the pigment when present, the distribution of 

 the pigment cells, and scale structure or other surface markings. 



In Class 4 the diameter of the fibres, the nature of the cell 

 walls — uniform thickness, etc. — the size of the lumen, and super- 

 ficial markings help in the recognition of the fibre. Polarised light 

 will often assist in this section. 



The microscope can also be used to determine: — 



(a) Whether the fibres are in their normal state or have 

 undergone treatment which has altered their shape. 

 IMercerised cotton is a good example. 



