Robert Boyle (1627-1691) was an Anglo-Irish physicist and chemist. He was the fourteenth son of Richard Boyle, one of the richest men in Britain at the time. He was educated at Eton College and later, when he was 11 years old, his father sent him on a tour of Europe. In 1642 he was in Italy when Galileo Galilei died; the event affected Boyle so much that he began to study Galileo's work and became a strong supporter of his philosophy. A year later, his father died in battle and Boyle returned to England to live with his sister. During this time, Boyle began studying at what he called "Invisible College," which would soon become the Royal Society of London.

Boyle made important contributions to physics and chemistry during his working life, such as discovering that sound cannot travel through a vacuum. Nevertheless, his most famous work was the so-called Boyle’s law, in which he stated that the volume of a gas is inversely proportional to the pressure. Thereafter, this law was complemented by Edme Mariotte, who added that this would only be true if the temperature is constant, becoming the Boyle-Mariotte law. In 1661, Boyle published a treatise entitled The Sceptical Chymist, where he detaches chemistry from the magic of the alchemy, believing that chemistry could be explained through atoms.

Another volume was published by Boyle in London in 1693, entitled Medicina Hydrostatica, sive, Hydrostatica Materiae Medicae applicate and written both in English and Latin. In this treatise, Robert shows that by weighting bodies in water, comparing the weight with the air and from there deducting the proportion of weight, the Specific Gravity of the body may be more exactly determined. The treatise is divided by 16 chapters,and, trying to give a general account of the various topics covered, a brief overview of each follows: Chap 1 is about the boles and less valued stones and how they may have great Medical Vertues, such as Gemms.; Chap 2 starts explaining the weight of bodies in water “How to discover practically the proportion in the weight, between the solid and the Liquor”.

Chap 3 is an account of several solid bodies. “A note that the greater or lesser weight of sucb bodies does not necessarily imply greater or lesser Medical Vertues, or Noxious Qualities in them”; Chap 4 explains how to find out whether a Mineral body propounded, as likely to be a stone, or of a stony nature; Chap 5 is about the resemblance or the difference between bodies of the same denomination.

Chap 6 is about how to discern genuine stones, such as Animas or Mineral, from counterfeit ones; Chap 7 explains how to estimates the genuineness or the degree of purity of several bodies; Chap 8 how to make hydrostatical inquiries into liquids, for instance Mercury; Chap 9 the way of weighting Hydrostatically the pouder’s of sinking bodies, small sands, or the fragments of greater bodies: An advertisement for the more exact weighing of these and others things; Chap 10 the way of examining hydrostatically a body that will dissolve in water, or easily mingle with it; Chap 11 how to find out by the hydrostatics, the gravity of fluid bodies; Chap 12 several ways to find out the weight of liquids in water; Chap 13 of what use this hydrostatical examination of liquid one in another, may be to physicians; Chap 14 two reasons why, in many cases its not necessary the scales employed in Hydrostatical experiments should be extraordinary good. An objection against the method of finding out weight of sinking bodies in Water, from the different weight of the water that may be made use, answered; Chap 15 Hydrostatical stereometry applied to the Materia Medica. How to find the weight of a cubical inch of water and how by means of this being found out, to find the dimensions of a solid heavier in specie than water; Chap 16 two questions answered. The first, whether he have proposed the best ways that can be thought of to examine bodies hydrostatically? The second, what credit may ne given to the estimates of the weight and proportions of bodies obtained by hydrostatical trials?

Boyle’s treatise is particularly widespread. It is present at the Portuguese National Library (BNP) in Lisbon, at the university of Seville in Spain, at the Complutense University of Madrid in Spain and at the University of Basque Country in Spain.