H. S. VAN KLOOSTER Rensselaer Polytechnic Institute, Troy, New York
As A disciple of Paracelsus, first and foremost of
the iatrochemists of the 16th and following centuries, van Helmout, known to all chemists as the originator of the term "gas," occupies a prominent place. Descended from a noble Belgian family, Jan Baptist van Helmont was born in 1577 in Bmssels. Early in life he studied philosophy and theology a t the University of Louvain. His interest in natural science and an inclination to serve his fellow men brought about a switch tomedicine, and in 1599 he took his doctor's degree. At first an adherent of Galenus (131-205), for many centuries the acknowledged medical authority in Europe, he later hecame a follower of Paracelsus (1493-1541). In contrast to the latter's stormy career, van Helmont's professional life was singularly uneventful. Although his life span coincided with the long stmggle of the Dutch for independence (1568-1648), it was spent mostly in solitude. Highly regarded as a physician and chemist, he visited London in 1604-05 but, unmoved by tempting offers of princes, he returned to his manorial estate of MBrode in Vilvorde near Brussels, where he died in 1644. Van Helmont's reputation as a chemist rests securely on ,his original investigations on gases which make h i m 4 0 quote the opinion of Ernst von Meyer-"the real founder of pneumatic chemistry." He was the first chemist who made a detailed study of carbon dioxide, which he called gas siluestre. The adjective "silvestre," meaning wild or untamable, referred to the fact that it could not be tamed or condensed. In one of his experiments van Helmont burned 62 pounds of charcoal and found a residue of one pound of ash. The other 61 pounds had disappeared as an invisible spirit. Writing in Latin, the official language of his time, he says: "Hunc spz'ritum, incegnitum hactenus, novo nomine gas voco" (this spirit, hitherto unknown, I call by a new name, gas). The term gas may have been derived from the Greek chaos, but it also resembles the Dutch verb for the fermentation process "gisten" and hence this too may have influenced van Helmont's ' choice. It is interesting to note that the term gas was not used by Boyle, Boerhaave, or Priestley and it came into common use only when Lavoisier re-introduced it toward the end of the 18th century. Van Helmont's researches on gas siluestre were quite extensive. He found that it is formed not only by burning charcoal, alcohol, and organic material, but also by the fermentation of beer and wine and by the action of
acids or vinegar on shells and limestone. He likewise noted its presence in some springs and caves. He observed, like others before and after him, the volume change in air when a candle burns in a closed space, without being able to explain this experiment. The predominant role played by water in naturally occurring processes was studied by van Helmont in long-continued and painstaking experiments. No one hut a first-class investigator would spend five years in raising a five-pound willow, placed in an earthen pot containing 200 pounds of dried earth, to a specimen tree of 169 pounds and three ounces, the pot having being supplied with nothing hut rain water or distilled water during all that time. The earth when dried and reweighed had lost only two ounces. No wonder that water was considered by van Helmont as one of the primordial substances, the other one being a i ~ t h two e "elements" he considered as not being transformable into each other. In this respect he differed from Aristotle who assumed four elemenk-earth, air, fire, and water-and even from his predecessor, Paracelsus,. who recognized three elementary snbstance~mercury, sulfur, and salt. As can be seen from the few examples given, van Helmont made good use of the balance as a scientist's tool. In this respect he was a worthy scientific ancestor of Lavoisier who is usually credited with the introduction of the balance as an indispensable piece of equipment in chemical laboratories. In spite of his remarkable chemical achievements, van Helmont was, nevertheless, a child of his time, being subject to the mysticism and superstitions of his century, such as transmutation, spontaneous generation, and the belief in a cure-all (alkahest). He mentions, for instance, the fact that he had received from an "adept" one-fourth of a grain of a powder with which he, himself, had changed eight ounces of mercury into gold. Van Helmont's collected writings were first published in 1648 after his death by his son, Franciscus Mercurius van Helmont, under the title "Ortus Medicinae, uel Opera et Opuseula Omnia." This work has been reprinted and translated repeatedly afterward. In addition to the picture of van Helmont reproduced a s t h e Frontispiece, there exists a 17th century print, adorned with the family coat-of-arms, on which both van Helmont and-his son are shown. On this print his given names are spelled "Joannes Baptista."
