The phrase "at first containing" is not correct and does not convey a clear meaning in written English.
It may be intended to describe something that initially includes or holds something else, but the phrasing is awkward and unclear.
Example: "The container was at first containing a variety of fruits before being emptied."
Alternatives: "initially holding" or "originally including".
The most powerful politicians resent being cut out of his government, which at first contained ministers from all the big factions.
The co-director Eric Johnson, of Ohio State University, hopes that the virtual library will become the Google Books of medieval manuscripts, though it will, at first, contain mostly fragments housed at universities and museums, and therefore in no danger of dismemberment.
Worried that the Yeardyes were going to sue the family if Choo failed to produce a full line, Choi hurtled into the void, sketching a collection of 30 shoes that at first contained only about six or seven stilettos.
Divided into four galleries, the first contains no clothes at all.
In their Supreme Court brief, Mr. Stevens's lawyers denied that any of the dogs in the videos were "ripped and torn," and they counted "at most, 25 seconds containing yelps" in the more than two hours of footage on the tapes.
The first and second incubation steps were performed at room temperature and the third, containing higher concentrations of cryoprotectants, at 4°C.
At first these contained all kinds of information - travel and hotel accomodations, agenda, and stuff like that.
The cast for this season, the cooking competition's fifth, does not at first glance contain a personality on the scale of Lisa Fernandes, Season 4's sneering antihero.
In contrast, from a UK perspective the consequences at first seem contained to a worry over whether M&S will have our pineapple and melon salads this lunchtime.
It created little stir at first but contained original ideas that, together with Dalton's more developed articles, marked the transition of meteorology from a topic of general folklore to a serious scientific pursuit.
