QUEKETT MICROSCOPICAL CLUB. 345 



methylated spirit, tlie residue on evaporation was crystalline. He 

 found the thin solution of much advantage in mounting such 

 objects as whole insects, and he had no difficulty in keeping out 

 dust during the evaporation of the solvent. 



The Chairman then called upon Mr. Wallis to read his paper on 

 " Microscopy as an Aid to Analysis." Analysis, said Mr. Wallis, 

 is often regarded as the work of the chemist, but other scientists 

 play their part and the microscopist takes a high place. There is a 

 limit to chemical and physical methods. The material may 

 be in a state of fine division when its structure can be revealed only 

 by the microscope. Microscopical methods are often quicker 

 than chemical, e.g. an ointment sent for analysis was at once seen 

 to consist of a fatty base and a starch paste. The microscope is 

 also of great assistance in toxicological work where the available 

 material is a very small quantity, the result being checked 

 chemically. Even a pocket lens is useful for examining seed 

 mixtures in cases of alleged poultry poisoning and seed adulter- 

 ation, or for the preliminary examination of partly ground poultry 

 and cattle foods. In this way Mexican dried flies or Mexican 

 cantharides have been found in certain brands of chicken spice. 

 Starches form an important group of substances identifiable 

 by the microscope. A woman alleged that someone had tried to 

 poison her by putting powder in her tea ; it was found to consist 

 of maize starch and yellow-coloured particles, i.e. custard 

 powder. In another case, some well water was complained of ; 

 it gave good chemical figures, but contained a number of bacteria. 

 A few grains of partly decomposed potato starch were found in the 

 deposit, and on examining the surroundings, the gully into which 

 the pump trough emptied was found to be broken and slop water, 

 including washings of potatoes, had been soaking into the ground 

 about the top of the well. After the gully had been repaired the 

 water was quite satisfactory. On another occasion the com- 

 position of an ointment was quickly found to be wheat starch paste 

 mixed with a fatty basis, many of the starch grains being found to 

 be partly gelatinised. In a case of suspected poisoning of a child 

 some pieces of firm slate-grey substance found in the stomach were 

 discovered to be pieces of unripe apple stained by iron phosphate 

 produced by the decomposition of some Easton's syrup tablets 

 which the child had eaten, thinking them to be sweets. Apple 

 pulp may be recognised in jam by finding parts of the endocarp, 



