STUDIES ON LAVOISIER'S EXPERIMENTAL METHOD

拉瓦锡著名的质量守恒定律在他1789年出版的《化学原理》中有明确的记载。但是，这不是他对法律的第一次陈述。当他进行定量实验时，他已经使用这个定律来检验结果，并在他以前的出版物中制定了它。起初，他的定律只是物质守恒的另一种表述。这对于一些不能直接测量的物质的质量的评估是有用的。当他开始对有机物进行定量分析时，这条定律的意义就改变了。氧气被发现后，他意识到水不是一种简单的物质，这是必不可少的分析，以确定什么是真正的组成元素。实际上，通过有机物的燃烧，我们主要得到水和二氧化碳。拉瓦锡不仅比较了反应中物质的质量和产物的质量，而且还比较了燃烧前后各元素的质量。他用这种分析方法非常困难地确定了乙醇和糖的组成。这就是为什么他在书中的“糖发酵成酒精”一章中表达了他的定律。这是他基于质量守恒定律的定量分析方法。但很快，他开始失去他在定量分析中的严格性：他很容易满足于按照他的定律计算他没有称过的物质的质量，而不是费心重复实验。

Lavoisier's famous mass conservation law is clearly mentioned in his Traite elementaire de chimie published in 1789. But, it is not his first statement of the law. When he carried out quantitative experiments, he already used this law in order to check the result and had formulated it in his anterior publications. At first, his law was rather an alternative expression of material conservation. It was useful for evaluating mass of some substance which was not directly measured. When he began to execute quantitative analyses of organic substances, the significance of the law changed. After oxygen was discovered and he realized water is not a simple substance, it was essential for analyzing to decide what were the true composing elements. In effect, by combustion of an organic substance, we obtain mainly water and carbon dioxide. Lavoisier not only compared the mass of substances in reaction and the mass of products, but also compared mass of each element before and after combustion. He determined the composition of ethyl alcohol and sugar by this analytical method with enormous difficulty. That is why he expressed his law in the chapter on "fermentation of sugar into alcohol" in his book. That is his quantitative method of analyses based on his mass conservation law. But soon, he began to lose his strictness in his quantitative analyses : he easily satisfied himself with calculating following his law the mass of a substance he hadn't weighed instead of taking pains to repeat the experiment We think it is because he had no more time to reiterate the same experiment during the agitated torment of the French Revolution.