CHEMICAL LAWS.

New Zealand Herald, Volume XVI, Issue 5473, 2 June 1879, Page 5

CHEMICAL LAWS.

Ms. C. A. Robertson delivered hia second lecture in the City East School, Wellesleystreet, on Saturday evening. The attendance was good, considering the weather, heavy rain having set in for some time previous to its commencement. -Mr. Worthington, the head-master of the City East School, took the chair. Daring the lecture the Hon. Mr. Sheehan, accompanied by the celebrated Maori chief Kewi Maniapoto and another . Maori, entered the lecture-room. Rewi appeared to admire the numerous experiments which Mr. Robertson made in illustration of, chemioal action. The lecturer commenced by referring to the most important parts of the previous lecture. He then gave a brief sketch of the history of chemical science, referring to Geber, astronomer and alchemistj the founder of the A rabian school. This school adopted the notion that there was some substance in the earth which was capable of transmuting the baser metals into gold, and of becoming a sovereign remedy for "all the ills that flesh is heir to." For more than a thousand years the ultimate object of all chemical research was the discovery of the philosopher's stone and the elixir of life, as these were termed. Modern chemistry dates from the latter end of last century. Priestly's discovery of oxygen, and that of Cavendish as to the composition of water, and those of Lavoisier, followed by those of Davy in regard to the compound character of alkalies, constitute the foundation of modern chemistry. The lecturer then entered into a description of the character of the knowledge which chemistry purports to give us, being generally the true composition of bodies, and certain properties belonging to these. He then graphically delineated those chemical changes which matter undergoes in passing from the mineral to the vegetable and animal bodies. The lecturer exhibited the nature of chemical action by a series of successfullyconducted experiments. In shewing the action of the saliva on the starch in food, Mr. Robertson did not succeed, in consequence of the specimen of bread whioh he used being adulterated with sugar. Thiß is a hint to our bakers. The lecturer then further explained generally the classification of food, and he spoke more particularly of mineral food, pointing out the great importance of water as a constituent of diet. He illustrated his remarks as to the organic impurities in water by testing three separate specimens with permanganate of potash. The first two specimens, namely, filtered and town water, stood the test, retaining the colour, but the third, from a surface well in the neighbourhood, shewed unmistakable signs of organic impurity, and was not in that condition a wholesome water. He related several instances in which dangerous diseases had been traced to the drinking of water apparently pure to the senses. In one instance, a severe outbreak of scarlet fever in a ladies' college, which caused several deaths, was traced to the drinking of water from a tank in which some red herrings were found decomposed. Cholera likewise had been produced by drinking impure water. The lecturer concluded by referring to the progress which had been made of late years in sanitary science. This was chiefly due to advancement in the knowledge of chemical laws. In olden times, when epidemics broke out, it was attributed in Christian countries to direct visitation of God, and in heathen ones to some offended deity. Although, as yet, no sufficient scientific explanation has been given of the origin and spread of these contagious diseases, enough has been demonstrated to shew that they emanated largely from uncleanlineas, and causes of that kind. Animal refuse in a state of decay is the material which furnishes the food for these poisonous germs, and water and air are the chief agents which convey these to the human body, The spectroscope and the microscope have rendered valuable services in these inquiries. Dr. Angus Smith, Dr. Frankl&nd, Professors Tyndal, Huxley, Roscoe, and other eminent scientific men, have earned the gratitude of suffering humanity in this respect. The most stj iking feature in fructifying causation was that the effects seemed altogether disproportioned to the causes which produced them. A vote of thanks was heartily accorded to the lecturer, who announced that his next lecture would be on " Carbonaceous or Heatgiving Food."