Touchstone (assaying tool)

For other uses, see Touchstone (assaying tool) (disambiguation).

A touchstone is a small tablet of dark stone such as fieldstone, slate or lydite, used for probing of precious metal alloys. It has a finely grained surface on which soft metals leave a visible trace.

Probing with a touchstone

By rubbing the metal on a touchstone a small amount of metal is ground off onto the stone, and forms a colored stripe. This is typically compared to a stripe ground from an alloy of known high-quality composition next to the sample (this is called "priming" the stone).

The simplest, but crude, method of probing is comparing the color of rubbed stripes, which varies depending on the amount of the base metal in the alloy. However, the standard probing method involves subjecting the stripes to graded solutions of acid which dissolve the alloys with lower content of precious metal but don't affect the alloys with higher content of it. Modern touchstone kits include the touchstone tablet proper, flasks of acids graded for standard alloys — e.g. 18K (karat) (75%) gold, 14K (58%), etc. — and priming pencils made from the standard alloys.

Use of the touchstone revolutionized the concept of money. Use of the touchstone in Ancient Greece and Anatolia dates to circa 500 BC. The fourth century philosopher Theophrastus in the tract de lapidibus (On Stones) described the testing of gold by fire or by the touchstone.

Prior to its introduction gold and silver were common currencies, but these could easily be alloyed with a less expensive metal (tin and lead were common). These were less valuable, but it was difficult to test for. The invention of touchstone made it possible to test for such forgeries quickly and efficiently, and also to determine the relative value of different alloys. That paved the road for gold and silver to become standard equivalents of value, and eventually to government-issued currency which began as coins of pre-probed alloys and weights guaranteed by the mint.

Touchstone metaphor

By extension, the metaphorical use of touchstone means any physical or intellectual measure by which the validity of a concept can be tested (see also Acid Test, Litmus Test, Shibboleth).

The character of Touchstone in Shakespeare's As You Like It is described as "a wise fool who acts as a kind of guide or point of reference throughout the play, putting everyone, including himself, to the comic test" (John Palmer).

Touchstone Metaphor Revision: By Sarah Mullins-Clonce April 4,2007

Touchstone is a term that applies to evaluating literary merit of a literary work. A touchstone is a short passage from the great master’s works of literature that is used in determining other poetry and artist's works of literature literary value or merit. (e.g. William Shakespeare's Romeo & Juliet, Edgar Allan Poe's "Fall of the House of Usher," Dante, Homer, Robert Frost's "The Road Not Taken," T.S. Elliot, etc.) This term was coined by Matthew Arnold. The merit of a literary work is determined by the quality of high truth and seriousness. Matthew Arnold’s essay “The Study of Poetry” gives Hamlet’s dying words to Horatio as an example of a touchstone. “Matthew Arnold as a Literary Critic” written by S. N. Radhika Lakshmi is an article that discusses Matthew Arnold’s literary criticism tools and techniques. In his article he states, “He also condemns the French critic Vitet, who had eloquent words of praise for the epic poem Chanson de Roland by Turoldus, (which was sung by a jester, Taillefer, in William the Conqueror's army), saying that it was superior to Homer's Iliad. Arnold's view is that this poem can never be compared to Homer's work, and that we only have to compare the description of dying Roland to Helen's words about her wounded brothers Pollux and Castor and its inferiority will be clearly revealed. Arnold's criticism of Vitet above illustrates his 'touchstone method'; his theory that in order to judge a poet's work properly, a critic should compare it to passages taken from works of great masters of poetry, and that these passages should be applied as touchstones to other poetry. Even a single line or selected quotation will serve the purpose. From this we see that he has shifted his position from that expressed in the preface to his Poems of 1853. In The Study of Poetry he no longer uses the acid test of action and architectonics. He became an advocate of 'touchstones'. 'Short passages even single lines,' he said, 'will serve our turn quite sufficiently(Arnold)’.(Lakshmi)”.

Works Cited

Arnold, Matthew. “The Study of Poetry.” Essays: English and American. Ed. Charles W. Eliot. 1909–14. Published April 11, 2001 by Bartleby.com. 4 Apr. 2007 <http://www.bartleby.com/28/5.html>.

Lakshmi, Radhika,S. N. “Matthew Arnold as a Literary Critic.” Literature-Study-Online. Ed. Ian Mackean. 2000-2007. 4 Apr.2007 <http://www.literature-study-online.com/essays/arnold.html>.

Bibliography

Arnold, Matthew. Essays in Criticism. Ed. S. R. Littlewood. London: Macmillan. 1958

Arnold, Matthew. Selected Poems and Prose. Ed. Denys Thompson. London: Heinemann, 1971

Arnold, Matthew. 'Preface to the First Edition of poems: 1853'. The Poems of Matthew Arnold. Ed. Miriam Allot, London, 1979. 654-671

By: Sarah Mullins-Clonce April 4, 2007