Alchemy can be thought of a science of old ages that led to the development of the science of chemistry. As a matter of fact the name chemistry is also derived from the name alchemy.
The science of chemistry developed as a result of efforts of people in earlier tomes to convert less valuable metals like iron into gold, and develop elixir of life. These efforts did not involved experimenting with subjecting many different kind of substances in many different combinations to different processes. These experiments gave the people knowledge and understanding of chemical nature and behavior of many different substances and their chemical reactions. Thus, though alchemy did not succeed in their original aim of either converting other metals into gold, or producing elixir of life id formed the foundations for development of the science of chemistry.
I personally like think of alchemy and chemistry as two different stages of development of the same subject, rather than two independent subjects. Alchemy has contributed substantially to development of science by forming the core around which modern day chemistry has developed. Thus I see no relevance in talking about modern age exercises on alchemy. It is the other way round. Alchemy has impacted the modern day exercises.
In modern age, alchemy has become marginalized.
Science was requiring more and more the need for experiment, the only way to verify the truth.
Robert Boyle (1627-1691) has given a new impetus to the scientific method of experimentation. In his researches in chemistry, clearly stated the futility of searching Philosopher's Stone.
Isaac Newton has studied several pages of alchemical literature and experimented in his laboratory the operations described here. Newton was hoping that this will clarify the structure of the micro universe, which to correlate with that of the cosmological.
Organic chemistry gives a blow to hybrid form of chemistry of Paracelsus and to the hope to find the elixir of youth, showing the toxicity of the substances alchemists were working.
With time, Ars Magna (and other esoteric subjects as: astrology, Cabala) was ostracized, excluded even from universities, giving it the epithet of superstition. It was left only at grassroots level, where credulity was gave it some influence.