518 REPORTS ON THE STATE OF SCIENCE. 



Repeat experimeut of heating wood and some food-materials iu hard glass 

 tube ; notice that gases evolved only burn in contact with air, and that the 

 charcoal produced will not burn iu the tube, but will burn in the air. 



Oxygen passed over heated carbon produces a gas which is acid, affects lime- 

 water, and will not support the combustion of a taper — carbonic acid gas. It is 

 similar to the gas exhaled from the lungs. Magnesium will burn in this gas pro- 

 ducing carbon and magnesium oxide, showing by analysis that carbonic acid gas 

 is composed of carbon and oxygen. 



A slow stream of oxygen passed over a column of red hot carbon produces 

 some carbonic acid gas ; but also large quantities of an inflammable gas — carbonic 

 oxide — ^often seen on the surface of a clear coke fire. The two oxides of carbon; 

 the nature of flame ; care and use of oil lamps. 



Revision lessons on the chief types of foodstuffs — starch and sugar, fat and 

 lean. All contain carbon ; some when burnt produce a pungent odour of burnt 

 feathers : these contain nitrogen, and are known as proteids. Flour contains 

 starch and gluten (proteid). Eggs contain albumen (proteid) and fat insoluble. 

 Starch is easily convertible into su^ar. Fats contain no nitrogen, but are usually 

 easily melted and rendered soluble by alkaline substances. 



The fermentation of starch and sugar by yeast ; production of alcohol and 

 carbonic acid gas. Distillation of a fermented liquor ; preparation and properties 

 of alcohol ; making and baking a loaf of bread ; the yeast used as a means of 

 making dough spongy by setting free carbonic acid gas in all parts. 



The nature of alcohol ; its value as a food and as a stimulant ; its effects on 

 the body when taken in excess ; it gives no additional strength, but acts as a whip 

 to the body, aud enables it to use its energy faster than it otherwise would. The 

 great dangers attending the use of alcohol. 



Yeast substitutes emploj'ed for the purpose of rendering dough spongy, so 

 that it will be easily attacked by the digestive juices, which must dissolve it 

 before it can get into the blood stream and nourish the body. The nature of 

 bread, soda, and baking powder ; the conditions under which they evolve gas. 



Fourth Year {about \A to 15 i/eajs of age). 



The chief sources of water-supply for domestic purposes; deep wells, surface 

 wells, rivers, lakes, rain ; the chief properties of these waters and the impurities 

 they contain. Evaporate to dryness iu a weighed basin a litre of rain water and 

 of the ordinary supply, and weigh the residue. Detection of organic matter by 

 potassium permanganate. The function of water as a food: acts as the solvent 

 and carrier of the food-material that nourishes all parts of the body, and is 

 necessary to the chemical changes continually taking place ; other domestic uses 

 of water, i.e., cleaning, draining, &c. 



Hard and soft waters : evaporate a litre of each to dryness and determine 

 ' total solids.' Notice difference in ' feel ' of each, and action of soap upon them. 

 Compare hardness of two waters by finding the least quantity of a soap solution 

 which will create a permanent lather with 50 c c. of each water. Boil some of 

 the hard water and again ascertain how much soap solution is required to pro- 

 duce a lather. Boil some hard water in a glass vessel aud notice what occurs. 

 Examine the 'fur' deposited on inside of kettle in which hard water is boiled. 



The various ways in which water may become contaminated. Special danger 

 of shallow wells near agricultural land. Drainage of cesspools and leaky drains 

 into water-supply. Necessity of periodical cleaning of storage tanks. Pollution 

 of rivers. If water is muddy it should be filtered through sand. Most dangerous 

 impurity is organic matter, as this mostly means the presence of germs of disease 

 (bacteria). If water is thoroughly boiled for fifteen minutes it may be regarded 

 as safe to drink, but not otherwise unless from a good town supply. Filters, 

 unless Tery frequently cleaned, are dangerous, as they may collect organiq matter, 

 and form a convenient feeding ground ior bacteria. 



Inflammable gas, originally called ' inflammable air,' is evolved in many cases 

 when metals such as zinc, iron, and magnesium are acted upon by hydrochloric 



