コメントを出した男 — 1931年の2ページから

出典：Ruth, Montonna & Montillon, Ind. Eng. Chem. 23, 850 (1931)

Ruthの名を聞けば、沪過に携わった人であれば「定圧沪過理論式」を思い浮かべると思う。1933年から35年の Studies in Filtration I〜IV の中で報告されている式だ。だが、その式が世に出る前に、2ページだけの短い文章があった。雑誌の編集者への手紙である。

1931年4月27日、ミネソタ大学化学科化学工学部門からInd. Eng. Chemへ送られた「Comments upon Recent Developments in Theory of Filtration」。差出人は B. F. Ruthら3名。その内容は、デルフト工科大学の van Gilseらが1930年から31年にかけて発表した一連の論文についてである。

その手紙の書き出しは、丁寧だが、どこか切迫している印象を受ける。原文を引用します。

In the light of some recent papers by van Gilse, van Ginneken, and Waterman [J. Soc. Chem. Ind., 49, 444T, 483T (1930); 50, 41T, 95T (1931) ] upon the subject of filtration, it seems advisable to call attention to an extensive program of research in the same field which has been carried out in these laboratories during the past two years and will be published as soon as released by the faculty of the Graduate School of the University of Minnesota.

Ruthらミネソタでは「この2年間、同じ分野の広範な研究を進めてきた」が、それは「大学院の公表許可が出次第、発表する」段階だった、と。つまり、自分の2年分の仕事がまだ世に出ていない間に、同じ題名に近い研究が先に発表されてしまった。その状態で、Ruthらは黙っていられなかったのだろう。許可待ちの研究の存在を、2ページの手紙で名乗り出たのである。

しかしこの手紙は、相手を否定するものではない。van Gilseらが唱えた結論について、Ruthらは「自分たちの研究でも確認された」と認めている。

出典: Ruth et al., Comments upon Recent Developments in Theory of Filtration, Ind. Eng. Chem., 23, 850 (1931)

その手紙は、続きの論文が近いうちに出る、という予告で締めくくられている。

結末 — 先に発表した側が残らなかった

van GilseらはRuthらよりも先に発表した。それでも、現代に理論式として知られているのは Ruthらの定圧沪過理論式だ。単位体積が通過する時間と積算体積の関係 t/V 対 V のプロットの考え方である。van Gilseらの式は標準にはならなかった。

ただし、Ruthもゼロから発見したわけではない。Lewis ら先人の知恵を整理し直した側面があることは、一言添えておきたい。この時代は、化学工学の単位操作を、経験の技術から理論へと組み上げていく時代だった。この手紙の締めくくりには、丁寧だが、どこか捻くれている印象(maligned; 不当に悪く言われた、貶められてきた)を受ける。原文を引用します。

It can be said with assurance that no other branch of chemical engineering lends itself more exactly to theoretical treatment and mathematical analysis and computation than does this much maligned unit process of filtration.

このような「名乗り」は、Museいわく当時としては、正規の作法だったらしい。 論文が雑誌に載るまで時間のかかる時代、編集者への手紙は「自分の仕事がここにある」と日付つきで記録に残すための、認められた手段だったらしい。

今では、この形そのものはほぼ見られないと思う。特許出願がそれに相当する認識である。内容が自然法則や原理なので特許にはならない（特許法第2条第1項）が、私の発明のように「利用した技術的思想の創作のうち高度のもの」となれば、特許権利化に繋げられる理解である。

English Summary for international readers

The Man Who Issued a Comment — From Two Pages in 1931

Anyone who works in filtration will think of the constant-pressure filtration equation when they hear the name Ruth — the equation reported in Studies in Filtration I–IV (1933–35). But before that equation appeared, there was a short text of just two pages: a letter to the editor of a journal.

On April 27, 1931, "Comments upon Recent Developments in Theory of Filtration" was sent from the Division of Chemical Engineering at the University of Minnesota to Industrial and Engineering Chemistry. Its authors were B. F. Ruth and two colleagues, and it concerned a series of papers published in 1930–31 by van Gilse and his co-workers at the Delft University of Technology.

The opening of the letter is polite, yet it carries a sense of urgency. I quote the original:

"In the light of some recent papers by van Gilse, van Ginneken, and Waterman [J. Soc. Chem. Ind., 49, 444T, 483T (1930); 50, 41T, 95T (1931)] upon the subject of filtration, it seems advisable to call attention to an extensive program of research in the same field which has been carried out in these laboratories during the past two years and will be published as soon as released by the faculty of the Graduate School of the University of Minnesota."

In Minnesota, they had spent the past two years on an extensive program of research in the same field — but it was still at the stage of awaiting release by the faculty of the Graduate School. In other words, while their own two years of work had yet to appear, a study with a nearly identical title had been published first. They could hardly have stayed silent. In a two-page letter, they announced that their research existed.

And yet the letter does not deny the other side. Of the conclusion put forward by van Gilse and his colleagues, Ruth and his co-authors acknowledged that it "was confirmed by their own research as well." The letter closes with a notice that the full papers would appear in the near future.

Conclusion — The Side That Published First Did Not Remain

The Delft group published first. Even so, the filtration theory known today is Ruth's constant-pressure formulation — the idea of the t/V versus V plot, the relation between the time for a unit volume to pass and the cumulative volume. The Delft group's equation did not become the standard.

To be fair, Ruth did not discover everything from nothing; in part, he reorganized the wisdom of predecessors such as Lewis. This was an era when the unit operations of chemical engineering were being rebuilt from empirical techniques into theory. The closing of the letter, too, is polite — yet it has a prickly, defiant edge to it. I quote the original:

"It can be said with assurance that no other branch of chemical engineering lends itself more exactly to theoretical treatment and mathematical analysis and computation than does this much maligned unit process of filtration."

Such an "announcement" of one's own work was, Muse — the AI assistant who helps me with this series — tells me, accepted practice at the time. In an age when a paper took long to appear in a journal, a letter to the editor was a recognized means of leaving a dated record that "our work is here."

Today, this form itself is hardly seen. I regard the patent application as its present-day equivalent. A natural law or a principle cannot itself be patented (Article 2, Paragraph 1 of the Japanese Patent Act); but when, as in my own inventions, it takes the form of "a creation of technical ideas utilizing the laws of nature, of a high level," it can lead to patent rights. That is my understanding.