| The | 1st | needle of | 23 | duellae | of silver and | 1 | duella | of gold. |
| " | 2nd | " | 22 | " | " | 2 | duellae | of gold. |
| " | 3rd | " | 21 | " | " | 3 | " | " |
| " | 4th | " | 20 | " | " | 4 | " | " |
| " | 5th | " | 19 | " | " | 5 | " | " |
| " | 6th | " | 18 | " | " | 6 | " | " |
| " | 7th | " | 17 | " | " | 7 | " | " |
| " | 8th | " | 16 | " | " | 8 | " | " |
| " | 9th | " | 15 | " | " | 9 | " | " |
| " | 10th | " | 14 | " | " | 10 | " | " |
| " | 11th | " | 13 | " | " | 11 | " | " |
| " | 12th | " | 12 | " | " | 12 | " | " |
| " | 13th | " | 11 | " | " | 13 | " | " |
| " | 14th | " | 10 | " | " | 14 | " | " |
| " | 15th | " | 9 | " | " | 15 | " | " |
| " | 16th | " | 8 | " | " | 16 | " | " |
| " | 17th | " | 7 | " | " | 17 | " | " |
| " | 18th | " | 6 | " | " | 18 | " | " |
| " | 19th | " | 5 | " | " | 19 | " | " |
| " | 20th | " | 4 | " | " | 20 | " | " |
| " | 21st | " | 3 | " | " | 21 | " | " |
| " | 22nd | " | 2 | " | " | 22 | " | " |
| " | 23rd | " | 1 | " | " | 23 | " | " |
| " | 24th | " | pure gold | |||||
By the first eleven needles, when they are rubbed on the touchstone, we test what proportion of gold a bar of silver contains, and with the remaining thirteen we test what proportion of silver is in a bar of gold; and also what proportion of either may be in money.
Since some gold coins are composed of gold and copper, thirteen needles of another kind are made as follows:—
These needles are not much used, because gold coins of that kind are somewhat rare; the ones chiefly used are those in which there is much copper. Needles of the third kind, which are composed of gold, silver, and copper, are more largely used, because such gold coins are common. But since with the gold there are mixed equal or unequal portions of silver and copper, two sorts of needles are made. If the proportion of silver and copper is equal, the needles are as follows:—
| Gold. | Silver. | Copper. | ||||||||||
| The | 1st | of | 12 | duellae | 6 | duellae | 0 | sextula | 6 | duellae | 0 | sextula |
| " | 2nd | " | 13 | " | 5 | " | 1 | " | 5 | " | 1 | " |
| " | 3rd | " | 14 | " | 5 | " | 5 | " | ||||
| " | 4th | " | 15 | " | 4 | " | 1 | " | 4 | " | 1 | " |
| " | 5th | " | 16 | " | 4 | " | 4 | " | ||||
| " | 6th | " | 17 | " | 3 | " | 1 | " | 3 | " | 1 | " |
| " | 7th | " | 18 | " | 3 | " | 3 | " | ||||
| " | 8th | " | 19 | " | 2 | " | 1 | " | 2 | " | 1 | " |
| " | 9th | " | 20 | " | 2 | " | 2 | " | ||||
| " | 10th | " | 21 | " | 1 | " | 1 | " | 1 | " | 1 | " |
| " | 11th | " | 22 | " | 1 | " | 1 | " | ||||
| " | 12th | " | 23 | " | 1 | " | ||||||
| " | 13th | " | pure gold. | |||||||||
Some make twenty-five needles, in order to be able to detect the two scripula of silver or copper which are in a bes of gold. Of these needles, the first is composed of twelve duellae of gold and six of silver, and the same number of copper. The second, of twelve duellae and one sextula of gold and five duellae and one and a half sextulae of silver, and the same number of duellae and one and a half sextulae of copper. The remaining needles are made in the same proportion.
Pliny is our authority that the Romans could tell to within one scripulum how much gold was in any given alloy, and how much silver or copper.
Needles may be made in either of two ways, namely, in the ways of which I have spoken, and in the ways of which I am now about to speak. If unequal portions of silver and copper have been mixed with the gold, thirty-seven needles are made in the following way:—
| Gold. | Silver. | Copper. | |||||||
| Duellae. | Duellae | Sextulae | Siliquae. | Duellae | Sextulae | Siliquae. | |||
| The | 1st | of | 12 | 9 | 0 | 0 | 3 | 0 | 0 |
| " | 2nd | " | 12 | 8 | 0 | 0 | 4 | 0 | 0 |
| " | 3rd | " | 12 | 7 | 5 | ||||
| " | 4th | " | 13 | 8 | 1/2 | 2 | 1/2 | ||
| " | 5th | " | 13 | 7 | 1/2 | 4 | 3 | 1 | 8 |
| " | 6th | " | 13 | 6 | 1/2 | 8 | 4 | 1 | 4 |
| " | 7th | " | 14 | 7 | 1 | 2 | 1 | ||
| " | 8th | " | 14 | 6 | 1 | 8 | 3 | 1/2 | 4 |
| " | 9th | " | 14 | 5 | 11/2 | 4 | 4 | 8 | |
| " | 10th | " | 15 | 6 | 11/2 | 2 | 1/2 | ||
| " | 11th | " | 15 | 6 | 3 | ||||
| " | 12th | " | 15 | 5 | 1/2 | 3 | 11/2 | ||
| " | 13th | " | 16 | 6 | 2 | ||||
| " | 14th | " | 16 | 5 | 1/2 | 4 | 2 | 1 | 8 |
| " | 15th | " | 16 | 4 | 1 | 8 | 3 | 1/2 | 4 |
| " | 16th | " | 17 | 5 | 1/2 | 0 | 1 | 11/2 | |
| " | 17th | " | 17 | 4 | 1 | 8 | 2 | 1/2 | 4 |
| " | 18th | " | 17 | 4 | 4 | 2 | 11/2 | 8 | |
| " | 19th | " | 18 | 4 | 1 | 1 | 1 | ||
| " | 20th | " | 18 | 4 | 0 | 2 | |||
| " | 21st | " | 18 | 3 | 1 | 2 | 1 | ||
| " | 22nd | " | 19 | 2 | 11/2 | 1 | 1/2 | ||
| " | 23rd | " | 19 | 3 | 1/2 | 4 | 1 | 1 | 8 |
| " | 24th | " | 19 | 2 | 11/2 | 8 | 2 | 4 | |
| " | 25th | " | 20 | 3 | 1 | ||||
| " | 26th | " | 20 | 2 | 1 | 8 | 1 | 1/2 | 4 |
| " | 27th | " | 20 | 2 | 1/2 | 4 | 1 | 1 | 8 |
| " | 28th | " | 21 | 2 | 1/2 | 11/2 | |||
| " | 29th | " | 21 | 2 | 1 | ||||
| " | 30th | " | 21 | 1 | 11/2 | 1 | 1/2 | ||
| " | 31st | " | 22 | 1 | 1 | 1 | |||
| " | 32nd | " | 22 | 1 | 1/2 | 4 | 0 | 1 | 8 |
| " | 33rd | " | 22 | 1 | 8 | 11/2 | 4 | ||
| " | 34th | " | 23 | 11/2 | 1/2 | ||||
| " | 35th | " | 23 | 1 | 8 | 1/2 | 4 | ||
| " | 36th | " | 23 | 1 | 4 | 1/2 | 8 | ||
| " | 37th | " | pure gold. | ||||||