Proximate principles of plants

Chemists grouping together of proximate principles of plants after 1750... 

What counted as the most significant chemical components or principles of plants changed considerably around 1750. Whereas by 1700 chemists were almost exclusively concerned with the ultimate simple elements or principles of plants—apart from a few individual exceptions, such as Simon Boulduc—, after 1750 the majority of chemists became more interested in the compound components or proximate principles of plants. The increase in collective attention the compound components of plants received from 1750 on did not entirely replace the search for the ultimate principles of plants. Instead, chemists began to establish an order of analysis by distinguishing between two kinds of plant-chemical analysis first, the analysis of entire plants and the organized parts of plants, which aimed at separating the more compound or proximate principles of plants and, second, the further analysis of the proximate principles into their ultimate components or simple principles. Whereas the lat-... 

F. L. Flolmes presented all later eighteenth-century plant analysis as the analysis of proximate principles of plants by means of solvents. Therefore we wish to emphasize that almost all eighteenth-century chemists we have studied actually also further analyzed the substances extracted fixrm plants by dry distillation. In so doing, many of them even tried to study the different proportions of the distillation products. Lavoisier s elemental analysis of plant and animal compounds continued to some extent an old tradition that was never given up when chemists became more interested in the proximate principles of plants. But Lavoisier also changed both the technique and the conceptual resources for analysis of the elemental composition of plant and animal substances. See also our explanations in chapter 14. 

The gradual development and prohferation of the new analytical technique by means of solvents was by no means a sufficient condition for chemists interest in and grouping together of proximate principles of plants. The great attention the compound proximate components of plants received by the middle of the eighteenth century was also spurred by developments in natural history and in the chemical theory of compounds and composition. 

The simultaneity of chemists collective acceptance of the StahUan theory of an order of chemical composition and their new interest in and classification of the compound proximate principles of plants is a coincidence that had important consequences. Stahl s theory reinforced a continuous development of chemists analytical practice, which in the decades before had been spurred mainly by chemists attempt to reconcile their analytical and pharmaceutical objectives. By the middle of the century, the theory of a graduated order of chemical composition lent a clear and distinctive voice to these earlier attempts. It was an important and new condition for the acceleration of an ontological shift, which may be easily overlooked when historical studies concentrate exclusively on events taking place in the laboratory. But there was a further condition, external to developments in the chemical laboratory, which contributed to this accelerated ontological shift. This third condition will be examined in detail in the next section. 

In the three decades that followed, most chemists studied the proximate principles of plants and animals without demarcating principles that fermented from principles... 

Bucquet s detailed experimental histories of materials regarded as compound proximate principles of plants demonstrate impressively the diverse provenance of these substances, either firom chemical experiments in the chemical laboratory or from the world of trade and commerce. Many of his specific varieties of proximate principles of plants were imported commodities also described in the contemporary pharmacopoeias. For example, the class of extractive parts of plants (see figure 13.7) assembled various chemical extracts separated from plants in the laboratory by decoction and subsequent evaporation as well as juices prepared on a large scale in the trade, such as the juice of Hypocistis, juice of Acasia, and opium. Bucquet described not only the way to obtain the latter three pharmaceutical simplicia from... 

Fourcroy s Class of Seventeen Proximate Principles of Plants (1782)... 

A controversy Are mineral substances truly proximate principles of plants ... 

If we take a look at the earliest lists of proximate principles of plants published in the 1750s, we see immediately that substances were included in these lists other than those which later became identified as organic substances (see figures 13.1—5 earlier in this chapter). Venel entered into his list of immediate principles a material that would not still appear four decades later, namely aromatic distilled waters. The aro-... 

It was not until the 1790s that chemists began to dismiss mineral substances from the class of proximate principles of plants. But despite their earlier debates, they did so without any explicit argumentation. Their exclusion of mineral substances from the class of proximate principles of plants is made manifest mainly through scrutiny of... 

What had happened in the period between 1782 and 1792 that spurred Fourcroy to select from the former class of proximate principles of plants only those that were composed of carbon, hydrogen, and oxygen, and in some cases also of nitrogen In 1789, A.-L. Lavoisier had proposed a new analytical definition of plant and animal substances that was to become a compelling proposition almost immediately after its... 

With Lavoisier s theory of composition and affinity, the designation proximate principles of plants became restricted to substances that shortly afterwards became... 

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