Subsequently to Wollaston’s day, many analyses have been conducted, by Marchand, Lehmann, Wurzer, and Langier, L’Heretier, Ebstein and Sprague. Of the various findings we append those by Marchand, Lehmann and one of later date by Ebstein and Sprague.
Marchand’s Analysis
| Urate of soda | 34·20 |
| Urate of lime | 2·12 |
| Carbonate of ammonia | 7·86 |
| Chloride of sodium | 14·12 |
| Animal matter | 32·53 |
| Water | 6·80 |
| Loss | 2·37 |
| 100·00 |
Lehmann’s Analysis
| Urate of soda | 52·12 |
| Urate of lime | 1·25 |
| Chloride of sodium | 9·84 |
| Phosphate of lime | 4·32 |
| Cellular tissue | 28·49 |
| Water, loss, etc. | 3·98 |
| 100·00 |
Ebstein and Sprague’s Analysis
| Uric acid | 59·70 |
| Tissue, organic matter | 27·88 |
| Sodium oxide | 9·30 |
| Potassium oxide | 2·95 |
| Calcium oxide | 0·17 |
| MgO, Fe, P₂O₅, S | Traces. |
It will be seen that all of them agree more or less closely as to the essential ingredients being uric acid and soda. According to Ebstein and Sprague they consist usually of almost pure biurate of sodium and potassium. But, as a rule, after a time calcium salts are deposited. Dunin, it may be noted, has found deposits resembling gouty tophi, which contained only calcium salts. Kahn, again, claims that tophi do not always consist solely or even largely of urates, but that these may be replaced by calcium salts. It may be added, too, that M. B. Schmidt has recorded, under the designation of “Calcium gout,” a case in which there existed a generalised deposition of calcium, and this in tissues other than those usually involved in “metastatic calcification.” But, to sum up, although there may be admixture of lime salts and organic matter, the salient chemical constituent of tophi is biurate of sodium.
Mode of Formation