Which are blackish - Or, rather, which are turbid. The word used here (קדרים qoderı̂ym) means to be turbid, foul, or muddy, spoken of a torrent, and then to be of a dusky color, to be dark-colored, as e. g. the skin scorched by the sun, Job 30:28; or to be dark - as when the sun is obscured; Joel 2:10; Joel 3:15. Jerome renders it, Qui timent pruinam - "which fear the frost, when the snow comes upon them." The Septuagint renders it, "they who had venerated me now rushed upon me like snow or hoar frost, which melting at the approach of heat, it was not known whence it was." The expression in the Hebrew means that they were rendered dark and turbid by the accumulated torrents caused by the dissolving snow and ice.
By reason of the ice - When it melts and swells the streams.
And wherein the snow is hid - That is, says Noyes, melts and flows into them. It refers to the melting of the snow in the spring, when the streams are swelled as a consequence of it. Snow, by melting in the spring and summer, would swell the streams, which at other times were dry. Lucretius mentions the melting of the snows on the mountains of Ethiopia, as one of the causes of the overflowing of the Nile:
Forsitan Aethiopum pentrue de montibus altis
Crescat, ubi in campos albas descendere ningues
Tahificiss subigit radiis sol, omnia lustrans.
vi. 734.
Or, from the Ethiop-mountains, the bright sun,
Now full matured, with deep-dissolving ray,
May melt the agglomerate snows, and down the plains
Drive them, augmenting hence the incipient stream.
Good
A similar description occurs in Homer, Iliad xi. 492:
Ὡς δ ̓ ὁπόε πλήφων ποταμός πεδίνδε κάτεισι
Χειμάῤῥους κατ ̓ ὄρεσφιν, κ. τ. λ.
Hōs d' hopote plēthōn potamos pedionde kateisi
Cheimarrous kat' oresfin, etc.
And in Ovid also, Fast. ii. 219:
Ecce, velut torrens andis pluvialibus auctus,
Ant hive, quae, Zephyro victa, repente fluit,
Per sara, perque vias, tertur; nec, ut ante solebat,
Riparum clausas margine finit aquas.

Blackish by reason of the ice - He represents the waters as being sometimes suddenly frozen, their foam being turned into the semblance of snow or hoar-frost: when the heat comes, they are speedily liquefied; and the evaporation is so strong from the heat, and the absorption so powerful from the sand, that they soon disappear.

Which are blackish by reason of the ice,.... When frozen over, they look of a blackish colour, and is what is called a black frost; and these either describe Job and his domestics, as some (h) think whom Eliphaz and his two friends compared to the above streams water passed away from, or passed by and neglected, and showed no friendship to; who were in black, mournful and rueful circumstances, through the severe hand of God upon them. The word is rendered, "those which mourn", Job 5:11; or rather the friends of Job compared to foul and troubled waters frozen over which cannot be so well discerned, or which were black through being frozen, and which describes the inward frame of their minds the foulness of their spirits the blackness of their hearts, though they outwardly appeared otherwise, as follows:
and wherein the snow is hid; or "on whom the snow" falling, and lying on heaps, "hides" (i), or covers; so Job's friends, according to this account, were, though black within as a black frost yet white without as snow; they appeared, in their looks and words at first as candid, kind, and generous, but proved the reverse.
(h) So Michaelis. (i) "super quibus accumulatur nix", Beza, "tegit se, q. d. multa nive teguntur", Drusius; "the frost is hidden by the snow", so Sephorno; or rather "the black and frozen waters".

blackish--literally, "Go as a mourner in black clothing" (Psalm 34:14). A vivid and poetic image to picture the stream turbid and black with melted ice and snow, descending from the mountains into the valley. In the [second] clause, the snow dissolved is, in the poet's view, "hid" in the flood [UMBREIT].

Which - Which in winter when the traveller neither needs nor desires it, are full of water congealed by the frost. Snow - Under which the water from snow, which formerly fell, and afterward was dissolved, lies hid. So he speaks not of those brooks which are fed by a constant spring, but of them which are filled by accidental falls of water or snow.